What made up the army around high middle ages?

There's no way to give an answer to the relative proportions of different kinds of troops in medieval armies in general as it varied too much over the time period, the nations and even different battles.

What we can say in more general terms was that most medieval armeis relied on a core of professional soldiers, originally knights and mercenaries but increasingly trained footmen came to become a part of this professional core too.

Added to this we also have feudal leavies, town militia and other types of infantry of very varying quality but there is no way to say in general terms how large a portion of an army was made up of each kind of troops.

Also, what was the biggest difference between a men-at-arms and a knight besides knights generally being of a noble family and being trained younger. I read somewhere the men-at-arms could fight nearly as well as knights? I hope i was clear about these questions, i'm not good with clarifying what i'm trying to ask.

A knight during the high middle ages was a social rank, a man-at-arms is a military function (specifically heavy cavalry). Therefore, a knight would generally fight as a man-at-arms but a man-at-arms was not necessarily a knight.