Time-Trial and Triathlon bikes differ from normal road bikes in that they are designed for maximum efficiency when riding alone (not in a group).
What, then, is the difference between them? Would there be something wrong with using a TT bike in a triathlon, or vice-versa?
There doesn't seem to be an objective difference between the two, and I often see them lumped together as a category. Is there a significant (if any) difference between them?