cRPG (computer role-playing game) is a term that came into prominence to differentiate it from table top role-playing, which was very big in the 80's and 90's. Nowadays it is generally used to refer to old school RPGs of the 90's, or modern games that take after their formulas. Usually the biggest difference between a cRPG and an aRPG (action role-playing game) is that cRPGs are heavily dependent on the character's stats, while aRPGs favour player skill. In most aRPGs you can defeat higher level enemies early on simply through being really skilled. In cRPGs if your character doesn't have the right stats or equipment, then they won't win. That's an incredibly simplistic but accurate difference between the two from a gameplay point of view.
There are three primary sub-genres of cRPGs. Turn-based (Fallout), real time with pause (Baldur's Gate) and BLOB, which can be either real time (Might & Magic) or turn-based (Wizardry). BLOB, or Blobber RPG, is a first-person cRPG in which you control an entire party through the lens of a single POV. Very small and niche sub-genre that one though.
Hopefully that helps a little.
How has no one said the feast from Hook!?!? Bangarang. Peter!