To my knowledge:
VAC = Detected a cheat in your memory and you are forever banned it won't be lifted unless it is incorrect.
Overwatch Ban/Game Ban = Convicted by people watching your competitive match and if cheating permanently banned.
Untrust Ban 1 = Quick ban to get cheaters off the game usually turns into a VAC ban after 24h
Untrust Ban 2 = Leaving comp games constantly, other comp issues etc, can be up to 365 days ban
Untrust Ban 3 = This is the one I have a question about because I got a permanent untrust after doing some semi-rage stuff in casual. I barely played MM. How I think it works is on official cs go servers if it detects "inhuman" movements like aimlock, aimbot, triggerbot (like really insane triggerbot) etc. After playing in community servers for a long time with hacks and was doing very good with them I never got this ban, until I played one game of casual then an hour later banned. I just want to know does this same "anti-cheat" apply in community servers? I know most clients like faceit, cevo, esea, esl detect cheats this way.
EDIT: Question: Can you be banned for purchasing another account on the same computer and network? This is assuming you deleted all traces of the hack and it is not a VAC ban but a game ban.