One choir hails from an Ivy League university, has a history that goes back 70 years and is in Singapore as part of its two-month world tour.
The other, just four years old, is made up of students with autism from a special education school.
But both share a love for music.
Harvard University's all-male a capella group Din & Tonics has been performing with the Pathlight Youth Choir from Pathlight School the past week, drawing the attention of the public in MRT trains, MRT stations and shopping malls.
A video of their performances has been shared on Facebook more than 7,700 times since last Wednesday, including once by Prime Minister Lee Hsien Loong.
GOOD VIBES ALL ROUND
You could see that the Pathlight kids all loved being on stage. It serves as a great reminder to us that performing for others is something special and we should appreciate the opportunities we have.
MR WILL JAROSZEWICZ, a member of the Harvard group, on singing with the Pathlight choir.
The performances culminated in a concert yesterday at A Very Special Walk, an event to raise funds for services for adults with autism.
The two music groups' partnership began in 2012.
Singaporean Huang Kaiyang, who has a brother who used to study at Pathlight, was then a member of the Harvard group.
So Din & Tonics, which usually tours the world every two years to raise funds for its operations, decided to support the autism cause on the Singapore leg of its tour.
Even though Mr Huang graduated two years ago, the Harvard group decided to continue its collaboration with Pathlight this year.
Mr Matthew Barber, 21, who also performed with Pathlight in 2014, said: "The Dins have had fulfilling experiences performing with Pathlight in the past. Singing for charity is very meaningful, especially for a cause we have a connection with."
While there are no Singaporeans in the group now, one member, Mr James Baskerville, 20, has a sister with a developmental disability and a Singaporean mother. He agreed that the collaboration with Pathlight was a meaningful one.
3 centres helping adults with autism have total annual deficit of over $1m
Services for adults with autism are the most costly programmes for the Autism Resource Centre (ARC) and Autism Association Singapore (AAS).
Three centres which offer such services - ARC's Employability and Employment Centre (E2C) and AAS' two Eden Centres for Adults - have a total annual deficit of more than $1 million, Central Singapore District Mayor Denise Phua told The Sunday Times.
This will be partly covered by yesterday's carnival-cum-concert, A Very Special Walk. It raised more than $600,000, surpassing the target of $500,000.
E2C offers job training and support. The other two centres cater to adults who have more severe autism and cannot work.
Ms Phua, president of ARC and a board member of AAS, said: "Children with autism grow up to become adults with autism. The need to stand by them and ensure that they continue to develop and learn does not go away when formal schooling is over.
"Adults with autism need all the support they can get in funding and inclusion in the community and workplaces."
Mr Will Jaroszewicz, 20, said: "You could see the Pathlight kids all loved being on stage. It serves as a great reminder to us that performing for others is something special and we should appreciate the opportunities we have."
During yesterday's show at Enabling Village in Lengkok Bahru, 10 members of the Harvard group - dressed in black tailcoats and lime green socks - stood among about 20 Pathlight School students. They sang Stand By Me and Bare Necessities, the popular song from the Disney film The Jungle Book.
Ms Nur Azimah Rahmat, 17, from the Pathlight Youth Choir, said: "I felt a bit nervous performing with these overseas celebrities, but I tried to hide the nervousness as I wanted to make sure that we performed well. I felt joyous and the atmosphere was really great."
Minister for Social and Family Development Tan Chuan-Jin and PM Lee's wife Ho Ching were among more than 2,000 people at the event organised by the Autism Resource Centre (ARC), which set up Pathlight, and the Autism Association Singapore (AAS).
Ms Ho Ching is adviser to ARC and patron of AAS.