there are many types of picks for many types of locks.
primarily, you will see rakes and SPP picks for the pin tumbler locks. however, there are many other types of specialty picks for specific lock types.
i am assuming you want to know what situation you would use XX pick.
hooks- single pin picking.
half diamond- SPP or raking.
snake- also known as the snake rake, obviously used for raking.
L-rake- known also as the sawtooth rake.
M-rake- some call it the batman rake.
ball- used for wafer lock raking.
half ball- used NORMALLY for wafer raking, however some have found usefulness for it as a pin tumbler rake.
double ball- known also as the snowman, rake as well primarily for wafers.
double half ball- or half snowman. wafer raking.
umm, what else...... i think that covers the basics and then some.
there are also many other specialty picks, such as raimundos bogotas. they are one in their own. usually used as rakes. (with either standard raking procedure, or with rais too much coffee method)
also, romstar is in the process of working on something called king and queen rakes. they are looking fairly interesting too.
and tons other picks for numerous things.
does that cover your question? if not, please tell us and we can help ya out.
oh, and there are also slimline picks that are used for restrictive keyways, and slimlines are simply slimmer and smaller, which allow for more moving around in the keyway.