[ygra]

TeX is the low-level typesetting system and programming language. LaTeX is a set of macros on top of that that try to support a more semantic approach to document layout. If you see long command names that more or less spell out what they do, it's usually LaTeX. If you see short, cryptic abbreviated commands it's usually TeX.

[AnimalMuppet]

And if you use either TeX or LaTeX instead of Lyx, you're a masochist.