Walker
They are not the same thing at all!
Captain - record hours against this when you are the captain, be it airliner or single engine piston
P1 - record hours against this total when you are co-pilot handling the sector
P2 - record your co-pilot hours here for aircraft requiring 2 crew and licensed on type
Dual - when under flying instruction, for your PPL or initial conversion training.
I'm now sure that someone will correct me, but that is the general idea.
Note: Each flight can only be recorded once!