Well if you're deploying a static site they are the same, but that's still not the whole picture. They have support for lambda style "serverless" functions and Fauna DB[1], and can bundle functions with apps automatically for some tools like Next.js to do server side rendering for dynamic routes[2]. So while they don't support quite the same level of custom stacks, backends and DBs, they do provide tools that enable full stack applications.

[1] https://www.netlify.com/tags/database/

[2] https://www.npmjs.com/package/@netlify/plugin-nextjs