Usually the higher rated player makes far less mistakes and can capitalize on the other player's mistakes quicker and easier.
What is the difference between NMs, IMs, and GMs?
The level of execution of a GM is higher than that of lower master levels. This can vary from person to person. To be honest there is not much difference other than the title being given a label. At a certain point it becomes a question of who can execute better than the other and who can do that execution at a higher level.
Other than given ratings,(2000, 2500, 3000) what are National Masters expected to know, as opposed to what International Masters know? Does it boil down to how far each calculates? or is there an advancement within their own scope of Tactics?