They are pretty much identical. Seed has better docs, Yew has a promise for multi-threaded stuff, but its not very well documented (or even working). I've tried projects with both and the nice thing with Yew is that the syntax for HTML is kinda compatible with the actual thing (think JSX.) Seed however is macros only. Both seem to compile in the same time, but I would bet there would be differences on bigger projects (which there are none atm?)