The two sites are not equatable. One site has simple rules, don't fight, put effort into your posts, make sure your posts are interesting to engineers. And they're known beforehand. The other just decides halfway through any controversy how they are going to handle it and usually errs on the side of being heavy handed. There's no telling beforehand just by reading ToS what Twitter will do.

I could probably say anything right now, and as long as I backed it up with data, or just thoughtfulness, I probably wouldn't be banned or censored here. I've never seen anything like that happen on this site. You can have free discussions here. You could, theoretically, have a free discussion on Twitter if you genuinely were not interested in discussing anything controversial. For most topics of disagreement though, on twitter you have to police your own speech.