RE: Newbie questions on broadheads
To carry it further, you have mechanical heads, replaceable blade heads, and low profile heads.
Dan covered the mechanicals pretty well. The only thing I would add is alot of people use them as a bandaid for a poorly tuned bow. I personally shoot mechanicals, but my bow is well tuned and I shoot them because of their massive cutting diameter. Mine are 2".
Replaceable blade heads are just what they sound....Muzzy is one, Magnus Stingers are another. Some of the heads in this category can either have the blades changed, or sharpened, such as the Magnus Stinger.
Low profile heads are catching on quickly because while they are a fixed blade head, they fly like darts because of their short profile. While they fly beautifully, they offer a small cutting diameter, usually less than 1". Heads of this variety would be the Slick Trick, Sonic, and Wasp Boss Bullet, just to name a few.
There are probably more broadheads on the market than any other piece of archery equipment. Choosing one is often a difficult, ardious task. But armed w/ the proper knowledge makes choosing one easier.