You didn’t answer the question. What makes stripe different from Square?
Square is focused on in person card transactions whereas Stripe is focused primarily on online transactions and supports multiple types of payment method (CC, ACH, ApplePay, Bitcoin, etc). Stripe also handles outgoing payments (marketplace, top-ups, etc) and is just now getting into in person transactions.
Stripe can make that little box you type your credit card painless, seamless and highly accessible for small and large companies. They are generally delivering a high quality experience throughout their process and many of their staff are generally awesome.
Full disclosure, I work at a big company and we use Stripe. I used to work at startups in the early 2000s and handled payment solutions. The world is better with Stripe.