[Capricorn2481]

Next JS hydrates the entire page as a react component, so it's SSR on initial site visit and then navigating from there requires rendering (and maybe you'll use SSR to get some props).

Astro is actually an MPA that allows some client side components, so it only requires you to render on parts of the page. I prefer that for content heavy sites because I'm not sure how much interactivity I need.

[leerob]

This is Next.js in the "Pages Router" world (e.g. everything prior to 13.4). Past 13.4, you can also use the "App Router", which is kind of like a framework in a framework. It uses React Server Components, which can run server-only without hydration. Thematically similar to islands.

[Capricorn2481]

Yes, these are pretty new though and I hear some people are having issues with the app router. Astro came before this release