They are pretty different in the details tho, with vercel for example you have turbo/repo/pack to handle monorepo bundling/caching.
Also Vercel's and Netlify's serverless function might be similar but ain't exactly 1:1 the same.
I think vercel is more powerful, netlify seems more oriented to frontenders or so to me, dunno
All of them are UX wrappers of AWS infra underneath anyways