wetsuit vs speed suit?

Wetsuits are thicker and designed to keep to warm, but a side benefit is that they are very buoyant.  They are only legal when the water is under 78 for USAT and 76 for IM (they may have changed those, but they are close).  If you race in an area with cold water, get a full sleeve wetsuit.  More money buys you greater flexibility in the shoulders and possibly more buoyancy.  I paid $150 for my Xterra and thought it was a great deal, but if I had $600 I'd get a TYR Hurricane.

Speedsuits are for use when wetsuits are not legal.  They do not help with buoyancy but basically streamline the body of anything that might cause drag.  Some are made of materials which claim to do much more.  Mine seems to help about a minute a mile or so.  Speedsuits are being phased out however, and they will only be legal in IM brand races a few more weeks if I understand correctly.  USAT is phasing them out over the next few years.