I've been researching this myself too. What I know now is this:
Beside the size difference in diameter between CAT5 and CAT6 cables, the other major difference is SOLID core versus STRANDED cores. For stranded core cables, the teeth on the pins are made to sink into the individual wires (you'll see some labelled as 2-pole or 3-pole to describe the number of teeth on a pin); whereas for solid core cables, the pins are a little longer (deeper) and are designed to straddle (or grab or pinch) the solid copper wire from both sides, in order to make contact with it.
Also not all CAT6 plugs come in 2 pieces. Some come in one and some also come I 3 pieces. That's just a matter of preference and made to make it easy for guiding the wires into the plug.
When buying plugs, also pay attention to the thickness of the gold plating. Cheap indoor plugs only come with 6 micron, good ones will have 50 microns.
Finally, there are TWO major manufacturers that make these plugs: commonly WE/SS Stewards, or the Tycon Electric AMP styles. Each have their own crimper dyes. TE AMP ones have pins that are a little closer to each other than the Western Electic ones. So if you use the wrong tool, you'll end up buggering up the plug.
And, all these come for shielded or unshielded cables... Shielded plugs have a metal wrap around them.
There, now you know.