For one, Meet has consistently the worst picture and audio quality at least in my experience. I daily have about 4 or 5 zoom meetings and 1 or 2 meet meetings per week so it's not a small sample. On a day where I'm pumping out zoom meetings in perfect quality, Meet will be degrading the video to the point where I can scarcely recognize people and having audio sync problems. In the last couple of years I seldom have had "meet" meetings where at least one participant doesn't lose sync, lose audio or just get kicked randomly, where these occurrances are (anecdotally, in my experience) much less frequent for zoom. It gets particularly bad when you get above a certain number of participants.

I don't recall meet being this bad a few years ago (I used to be at a company that used it for all internal meetings) so I don't know whether some infrastructure changes have occurred to make it so.