What such tools actually do?
Foxmarks and Google Browser Sync are Firefox extensions used to synchronize bookmarks across different computers. This is extremely useful if you have firefox at home, at work and on a notebook used to surf the web.
The differencies
Google Browser Sync for Firefox is an extension that continuously synchronizes your browser settings – including bookmarks, history, persistent cookies, and saved passwords – across your computers. It also allows you to restore open tabs and windows across different machines and browser sessions.
Foxmarks, on the other hand, does NOT sync passwords, history, cookies and logins. Nor it sync open tabs. This is definitely useless to me.
This is what Gina Trapani from Lifehacker says on her article Yes, Foxmarks beats Google Sync when it comes to bookmarks.:
Unlike Google Sync, which will log you off of one computer where you have it installed if you come online at another, Foxmarks syncs across your computers while they’re all running. For folks like myself with a laptop and a desktop often online at the same time, this is a godsend. So, farewell Google Sync! It was a brief but bittersweet affair. Foxmarks is my honey now. Thanks, um, everyone! (Note: Foxmarks does NOT sync your history, cookies, open tabs or passwords like Google Sync does.) — Gina Trapani
Now I think the key point is missed. Foxmarks let you view your bookmarks “from any computer” connected to the internet. What this means is that you don’t need any extension to surf your faved sites. Just an internet connection, a login and a password for the service. Done.
If you “just” want to sync bookmarks, then go for Foxmarks. If you, like me, need something more than just bookmarks (history, persistent cookies, saved passwords and tabs/sessions) then Google Browser Sync is what you’re looking for.
Know what? I use both of them. Have fun and stay productive.