difference between IE25,CF01,IE01

What's the diff between IE01,CF01,IE25. when to use each of it?

i) when i create PRT using CF01, i can assign in routing/insp.

when i create equipment using IE01 with category Q( test equipment), i can assign that equipmnt to operation.

ii) when i create equipment using category P(PRT) in IE01, system does not assign PRT to operation in routing.

iii) when i create PRt using IE25, i am unable to assign the PRT to a operation in routing.

please let me know in detail, as i have a confusion of which to use when?