If the seeds are different, then they're probably different Guanabana (Soursop) varieties.
In my experience, people consider all Guanabanas to be the same variety. But I suspect/am-quite/certain that there have to be different varieties and that it's just that they haven't gotten aroung to categorize them.
A Guanabana tree is a beautiful tree that produces spectacular, large, good tasting fruit.
The trouble that I've had with Guanaban fruit trees is that when there's a winter freeze, the tree is weakend and will subsequently easily die.
This has happened to me, even though I'm in Zone 10b, Miami, FL, U.S.A.
I wish there was a cold tolerant Guanaban variety that I could obtain, in order that the tree doesn't die, when the temperature gets very low in the winter.