The main difference is the alpha cuts in the HUD. The bodies Vania, Frida, Selena, Xandra, Natasha are much light and dont have this system to get a better response in crowded sims, intended for roleplay sims or people that love the simplicity and low lag.

It take 3 hours approximately for last users, the first can take 30 seconds.

First step is to convert the body and head to BOM. If you have a head with universal neck, actually most are universal, then select neck B. If you have the classic head from Second Life then select neck C. If you have an old head from Genus the model Strong, then select neck D. If your head is not standard as the others mentioned then set neck A.