VSTs and VSTis, DXs and DXis, generators, and plugins.....
A plug-in is a application that you can connect to another application, for instance, in fruity loops, you can have a plug-in to compress, EQ, flanger, etc
VST and DX are types of plug-in.
DX is the abreviation of Direct-X. Those are used mostly by Sonar, Soundforge & Acid... they use the DirectX of winXP... again, I could go into details, but... Let's just say that since DirectX is a winXP/Win2000 protocol, there is less latency with those plugins.
VST is an abreviation too, but I dont remember what
S)... that format was made before the DX and can run on PC and MAC (the other one cant since DirectX is a windows protocol)... It's commonly associated with Cubase, but can run on a bunch of other programs
Most plugins are can be found in the VST format, since it's more compatible than the DX. The only plugin I can thing of which is not in VST form is one called WAVES (which is a great plugin, by the way).
There are other types of plugins, but I dont use them at all, so I dont know them...
A generator generates sounds... it's kind of a synthertiser... I could go into details about how those work, but other peeps here are more knowledgable on the subject. Most of the time, they are also plugins, since you can add them up to another sequencer program (like fruity loops). They are instruments. So you can find some that sound like a drum, like a bass, a string, some electronic effects... birds chriping, monks singing, you name it...
Those generators can be made on the DX or the VST protocol. When they are, A DX generator is called a DXi and a VST generator is called a VSTi (i for instrument)....
Well, that's it!
If i made a mistake there, feel free to correct me guys (and girls)
by the way, dog... this is something you could have looked up yourself on the net... it's not that complex of a question, really... (no diss... but) you gotta read up if you wanna know stuff. The net is full of infos that are real helpfull