Comment by setopt

It's right on their support page. They also have a search function, just type in "Sync" and you'll get there.

https://www.waterfox.com/support/how-do-i-set-sync-my-comput...

Also, no, the page is not "sparse" on how it differs from Firefox, it's clearly explained https://www.waterfox.com/#why-waterfox