Here is every way they are dissimilar off the top of my head.
1: Demographics: Chauvin was a trial in a deep blue city in a deep blue state. Rittenhen is in a trial in a lean blue city in a solid purple state.
2: Defendants: Chauvin was a thoroughly unlikable piece of shit, at best apathetic to what he had done. Rittenhouse is a thoroughly likeable, if terribly naive, kid who actively regrets what he had to do.
3: Judges: Chauvin trial had an at best apathetic judge at worst actively pro Floyd. Rittenhouse trial has a fair judge, who leans Rittenhouse.
4: Juries: Chauvin trial had out and out activists, deeply ingrained, with enough black people on it in the summer of BLM, for a black victim, and who had a strong anti-cop stance. Rittenhouse has 11 women, some mothers, no systemic bias throughout at all.
5: Threats of riots: prior to the chauvin verdict or even -the trial- there were massive threats of violence and unrests which permutated the culture before the jury was even selected. For this one, there hasn't been a peep about it until midway through the trial, and even that has been barely even tepid at best.