PYEONGCHANG (AFP) - South Koreans angry at North Korea's perceived "hijacking" of the Pyeongchang Winter Olympics have sarcastically dubbed it the "Pyongyang Games", but it seems many really are struggling to differentiate between the two places.

Hundreds of Twitter users in recent days have referred to "Pyongyang2018", and while some were making a dig at the presence of North Korea at the Games, in many cases it appears to have been a simple mix-up.

The two are easily confused, but there is a world of difference between them: Pyongyang is the capital of nuclear-armed North Korea, while Pyeongchang is the South Korean region hosting the Winter Olympics.

The number of mentions of "Pyongyang2018" spiked during Friday's opening ceremony, when hosts South Korea and the North - two countries technically still at war - marched together behind the Korean unification flag.

The growing number of apparently unintentional references to Pyongyang irked at least one Twitter user in Washington, DC, who tweeted: "The number of people mistakenly using #Pyongyang2018 to tweet about #PyeongChang2018 is not that surprising but nevertheless upsetting."

It isn't the first time Pyeongchang has been confused with Pyongyang.

The gold medal for mix-ups goes to the Kenyan delegate to a UN conference held in Pyeongchang in 2014, who mistakenly flew to Pyongyang instead.

Landing without a valid visa, he was interrogated for five hours by North Korean customs officials and fined US$500 (S$664).

Eager to differentiate, provincial authorities have since re-branded the South Korean ski resort as "PyeongChang", using an upper-case "C".