Absurdly lax qualifications for margin and higher-level options trading.
Today, not too much. They have cleaner support for things like crypto or more unusual trade structures but the big thing that they offered that nobody else had was free trades. The whole industry has now shifted to that but it was a big deal when a trade was $0.00 rather than $4.95.
Better UI/UX. Less cluttering and refined.
But other brokers are for more power users
I use Fidelity and Webull. I have no strong preference. They both get the job done.