User Interface and Ease
Snaptube has a clean and simple interface that many users like but TubeMate also easy to use and familiar for longtime users.
Download Speed and Formats
Both apps support fast downloads but Snaptube offers more video formats and resolutions to choose from which can be handy.
Supported Sites
Snaptube supports many more websites for downloading videos while TubeMate mostly focuses on YouTube and few others.
Ads and Popups
Snaptube shows less annoying ads compared to TubeMate but both apps have some ads since they are free.
Extra Features
Snaptube has built in music player and supports playlist downloads TubeMate is more basic with fewer extra features.
Final Thoughts
If you want more options and features Snaptube may be better but if you prefer a simple YouTube downloader TubeMate works fine too.