What is the difference between INJ and REM in DAZ, and why do neither of them seem to work?

INJ is to Inject the character morphs, and REM is to remove the character morphs.  You have to own the morphs the INJ pose is calling in order for them to work on the character.
What are you doing for them not to work?

Thanks for the reply. 
Rem= Remove, oh... duh.
Ive been messing with Vic 4.2 and have got a pretty good handle on posing/rendering etc.  Now its time tio give her some personality, so I went out and downloaded a bunch of free characters, clothes etc.  I am thouroughly confused on why some work and some dont.  I want to start with a nude figure, with hair and nipples.  For instance, I got creeds Eliza.  When I select Victoria, and select the eliza mat, nothing happens.  If I change the diffuse color to refer to her file, she gets huge eyeballs across her torso!

Are you sure the character is for Victoria 4 and not an earlier version of Victoria? If it was an earlier version then the material names would be different, so DS would read through the file and find nothing that applied to V4. In any event, it sounds as if you are applying the head texture (or eye texture) to the body when you try to do it manually.

Ahhh....
Yes, that makes sense too.  I remember seeing ElizaH and ElizaB files.  Eliza HEAD and Eliza BODY.  How is a newbie supposed to know what all these damn abreviations are for?  Thanks, and I'll try again.  Is there a good place for a neophyte to go for some learnin'?

If it has just head and body textures that sounds like at best Victoria 4, more likely Victoria 1/2 (V3 would have separate eye maps).

Attached Link: Acadia's Tips and Links

Try the link up at the  top. It has some great information by Acadia for new users and most will apply whether it's Poser or Studio you're using. Scroll up to her previous reply.

And I sent you a PM with a couple of links, scottbaldassari.