Overall talent level. Almost everyone I've interviewed with at Google impressed me, as well as came across as thoughtful and kind.

I did interviews with many teams at Microsoft (9 technical interviews total) and the only person that impressed me is now at OpenAI.

Every single interview question I got at Microsoft was straight out of intro to CS /classic Leetcode.

They would straight up ask "find all anagrams", "string distance", "LCA of a tree".

Google instead disguises many classic CS questions, so it takes a lot more thinking. Microsoft seemed to just verify that you can quickly regurgitate classic algorithms in code.

I'm sure there are some great teams at Microsoft: but because each division/org is much more silo'd I think it's more likely a team has a lower overall bar.

Google makes everyone pass through a hiring committee and you're interviewed by people that have nothing to do with the team you might end up on. Meta is similar. Amazon has the team interview you, but they also have bar raisers come from other teams.

Microsoft seems the outlier here that someone can get on a team with only interviewing with people on said team.