On Twitter you follow people, on a site like Reddit you subscribe to subreddits.

Switching between accounts on Twitter means your follows/followers are lost, switching accounts on Reddit doesn't lose you anything (unless you're subscrived to private subreddits or are a moderator for a subreddit)

Twitter sometimes requires a verified email and phone number, which I assume they globally ban when they can. Not sure how effectively they are, but they do at least something make throwaways harder than Reddit does.