Not a whole lot. Definitely not $2/month worth of differences.
Overall, Sync is less buggy and has a nicer UI than other apps. It lets you customize how you want to see content a lot more, with 6 different layouts (from compact to full cards) and has everything you need for quick actions and gestures. It’s just one of the more feature complete options because it has 10+ years of development behind it.
Other apps may get there eventually, but right now Sync is one of the best.