[Eoussama]

As the title says, sometimes I mix up among the two, so do you guy have some accurate answer?
Thanks in advance

[PrO.GameR]

Interior is GTA:SA's way of making different worlds, VW is sa-mp's.
Virtual worlds were designed to give developers the ability to create well.. different worlds, interiors were designed by Rockstar so the game wouldn't render interiors while a player isn't in any.

[SickAttack]

Keeping it short and simple:

Interiors = the inside of buildings - "i n t e r i o r s"
Virtual worlds = independent from interiors, like time travel, I am in the present, you in da future! We do not coexist in each others' environment - "d i f f e r e n t . s p a c e . a n d . t i m e"