I found it quite surprising to find both Eurasian Tree Sparrows and House Sparrows in the same place in Ho Chi Minh City!
I don't remember seeing them together in any city in the world.
While in Europe you won't find any Eurasian Tree Sparrows in urban areas, you will find Eurasian Tree Sparrows in almost every city in Asia.
House Sparrows are much rarer in Asia.
Male and female House Sparrows look different while male and female Eurasian Tree Sparrows look similar.
If you want to tell the two sparrows apart, remember that Eurasian Tree Sparrows have a brown cap and House Sparrows have a grey cap.

1st, 2nd & 3rd photo: Ho Chi Minh City, Vietnam, 21 December 2023
4th photo: Ben Tre area, Mekong Delta, Vietnam, 22 December 2023
5th photo: Hoi An area, Vietnam, 1 January 2024