the one in the picture, that is the superior of superior strains, in fact it is the only one commercially produced. It is seedless, and sweeter than any another variety here in Thailand, except for perhaps some recently introduced ones that aren't on the market yet. If you are going to plant any variety then that is the one!
It is a bit of confusion here as well, all 'rose apples' are called "Chompuu" which almost sounds like Shampoo.
The jambos variety is very uncommon here and called Chompoo Nam Dog Mai - "flower water rose apple" I have seeds I brought from Hawaii and planted, but other people who are growing likely got from Malaysia, some nurseries sell these now.
Malaccense- definitely the "mamiew" variety, but called "Chompoo Mamiew", large red, pink red flowers, sweeter than wax jambu. I have several Mamiew trees on my property, fruit flies again get them, and they have problems with too much water uptake, deformed fruits, fungus on leaves, etc.. many problems with these trees, which I guess would be my climate having a very short dry season.
Then there are many other varieties, but not sure what they are, if just identifying by color of flowers then I guess easy. The wilder ones like on my property, at the temple and schools in my neighborhood are massive trees that nobody cares about or eats, they sweep them up with a broom and throw away, I feed mine to the pig. They are very small.