No difference. I hold a quite simple view on Testing, and even Agile. Frankly, I found a lot debating on terms very little meaningful. For me, Cover every user story with at least one E2E (via UI) test, and run the whole suite multiple times a day. If PASS, deploy to production.

Anyone can do with 5 or 10 tests. Of course, the challenge is manage and maintain a suite with a large number of tests. I worked out a formula to enable me to achieve that.