While the Samsung phone in your hand may be running the same Android operating system (OS) as your friend's Xiaomi or LG mobile phone, what's on each of your phone's screen may look very different.
The most obvious difference is aesthetic, in the way the phone's user interface (UI) is designed.
Then, there are the functional differences as a result of manufacturers' software tweaks to give their users a different mobile experience.
From call recording to space optimisation, Android device makers are slipping in added functionalities in order to differentiate their products from their competitors'.
"Consumers stick to a particular brand at times because they are familiar with the brand's user interface," said Gartner research director Anshal Gupta.
The fight to create brand loyalty is very competitive, given that Android phones now account for 83.7 per cent of the global mobile phone market, according to the IDC Worldwide Quarterly Mobile Phone Tracker research report released at the beginning of this month.
Mr C.K. Lu, a principal research analyst at Gartner, added that UI design is important in the smartphone replacement market.
"Consumers buying their second or third smartphone usually stick to the UI best suited to them," he said.
The online developer community is also rife with custom UIs, called ROMs (read-only memory) that more technical users can flash - the term for replacing a phone's operating system - on their phones. These custom UIs include the popular Cyanogen and Paranoid Android.
China phone manufacturter Xiaomi started out as a software firm working on its MIUI ROM in 2010 before it released its first smartphone a year later.
But with Android's open-source philosophy, users are free to change the look of their phones any time by downloading launcher apps from the Play Store that let them customise how the phone looks.
Teacher Joshua Loke, 27, said he prefers UIs that are clean and free of bloatware, like the one on his LG G3 which runs LG UX.
"It's just irritating to have redundant apps," he said.
The Straits Times Digital looks at eight UIs from mobile phone manufacturers and the standout features of each one.
These phones are all running on Android 6.0 Marshmallow, with the exception of the Xiaomi Note 3 and Asus Zenfone Zoom which run Android 5.1.1 Lollipop.
Stock Android is often the UI of choice for Android purists who insist on having the operating system the way Google intended it to be.
Only mobile phones under the Nexus line, which come directly from Google, ship out with Stock Android.
Stock is where you can plainly see Google's Material Design philosophy. Everything is clean, minimalist and vibrant, from the way the "recent" apps drawer expands, to how the transparent notification bar looks and works.
The main advantage of having Stock Android lies in how stock phones are always the first ones to get the latest Android updates directly from Google.
For instance, those who purchased the Nexus 6P last November were able to get their hands on Android 6.0 a few months before the rest of the world.
Stock Android also has the advantage of shipping with minimal amounts of pre-installed apps. Manufacturers may sometimes be overzealous in adding their own custom apps in their phones, resulting in multiple e-mail, contacts or camera apps within the same phone.
Stock Android also comes with deep Google Now integration. Swipe the homescreen to the left and you'll be taken to a page filled with "cards" that highlight important and timely information customised to you, such as traffic conditions on the way home or the status of your online package delivery.
Huawei Emotion UI
Huawei's latest UI, Emotion UI 4.1, is designed to work with Android 6.0 and has its own little tweaks to the operating system.
Unlike other Android UIs, Emotion does not come with an apps drawer. Instead, apps you download are all lumped on your homescreen, like on iOS.
And like iOS, you can swipe down on the home screen to activate a search bar for your apps, contacts or messages.
A nifty feature is the ability to record the phone screen.
It can be used to record games, for example, to share with your friends.
It also comes with the ability to scan business cards and store contact information onto the phone or your Google account. This is done through the scan option in the Contacts app, and the feature is reasonably accurate in picking up phone numbers and e-mail, although there is the occasional hiccup.
There is also a "mini screen view" that shrinks the display to about 70 per cent of the screen, which you activate by swiping on the navigation panel at the bottom of the phone. This is useful for people with smaller hands who may require one-handed use on larger Huawei phablets like the Mate 8.
Xiaomi's MIUI takes its inspiration from rival Apple's operating system iOS. The large, colourful icons on the latest version tested, MIUI 7, are designed to be visually intuitive.
The UI also does away with an apps drawer, which means, like with an iPhone, any apps you download from the Play Store stay on your home screens.
To make things easier on users, MIUI has a batch uninstall mode where users can select multiple apps and swipe them altogether into the bin.
The UI also comes with an in-built call-recording function. Simply hit the option while on a call and it will save the conversation as an mp3 file.
Those who want additional security for their text messages can also make use of MIUI's privacy mode in the default messaging app. Choose a contact whose messages you want to keep secret, and it will be accessible only with a passcode.
Message contents from these contacts will also not pop up in the notification bar.
There is also a nifty Read mode that filters out blue light from the screen, turning the screen warmer and yellower. Such blue light can disrupt the body's natural sleep pattern, especially at night, which makes Read mode ideal for those who use their phones before going to bed.
MIUI also lets you adjust the text size of your phone, from extra small to small (regular text size) all the way to XXL (where a few lines in a message can take up the entire screen).
Sony Xperia UI
Sony's Xperia UI is a colourful take on Android that remains quite faithful to the clean feel of Marshmallow's material design.
Visually, Sony has adapted the regular round stock app icons and made them into even funkier and more colourful ones. But, other than that, the settings menu and pull-down notification panel are very close to Stock the Android Marshmallow OS.
Swiping to the left while in the apps drawer gives you suggested apps to download, based on popular apps in the Play Store.
The Xperia line is known for its long battery life, and the Stamina mode feature in Sony's phones allows users to maximise their battery.
While in that mode, background data and GPS connectivity are reduced to prolong battery life. There is also an ultra stamina mode to eke out every last bit of juice, bycutting all but the basic functions to the phone, such as making and receiving calls or sending messages.
Xperia also comes with an image-enhancement feature that makes images on-screen sharper and brighter, so that pictures have more pop.
Samsung's TouchWiz interface can be found on its phones and tablets, and the latest Marshmallow-based TouchWiz 6.0 officially rolled out with the release of the Galaxy S7 and S7 edge in February this year.
The default white-and-blue theme is a study in contrasts, with bright, vibrant icons and azure blue headers against light backgrounds. While the rounded-corner square icons are clean and relatively minimalist, they do feel a bit cartoony.
Samsung's Theme Store has plenty of different skins.
TouchWiz has a range of helpful shortcuts, such as double-tapping on the home button to launch the camera, and swiping the screen with the palm to capture a screenshot.
There are also features that aid multitasking, from using two apps in split-screen view to using a single app in Pop-Up mode, which allows users to run the program in a separate movable window.
TouchWiz on the S7 and S7 edge incorporates an Always On display, which can permanently show information such as the time or a calendar without having to wake the phone.
The Game Launcher tool is a useful feature for avid mobile gamers. It shows up as a bubble when a game is launched, and tapping on it brings up a menu that allows users to access a suite of gaming-related functions, such as locking soft keys, recording gameplay, or tweaking resolution and frame rate.
Earlier this year, Asus released a list of devices that will be upgraded to Android Marshmallow in the second quarter of this year. However, it is now the middle of June and there is still no news on the update.
The current ZenUI is built on Lollipop, which means that it does not have Marshmallow features like managing individual app permissions and the Doze battery-saving system.
The new ZenUI should integrate such functions, and the company did also say that three Asus apps - Messenger, Mail and Calendar - will be replaced with their Google counterparts.
The look of ZenUI leans towards softer shades, with a lot of the icons being white-on-pastel depictions.
One highlight is the What's Next feature, which acts as sort of a personal concierge. It integrates information across a suite of Asus apps such as Calendar, Email, Messaging and Weather, and creates a personal timeline with alerts for the user.
ZenUI also comes with quite a bit of pre-installed software, such as MiniMovie (a video editor), Splendid (to change the colour temperature of the screen), Dr. Safety (a security app) and AudioWizard (an audio equaliser).
While I do think that a lot of the apps are useful, it may be cleaner if some management apps such as Splendid and AudioWizard are integrated into the Settings Menu.
For example, Splendid's screen functions could be subsumed under the Display menu in Settings, and AudioWizard could be part of the Sounds menu.