Tutanota doesn’t share their security audits, which Proton does.

Also, IIRC Tutanota uses their own custom encryption implementation, while Proton contributes to open source OpenPGP projects.

And when in the past the the Swiss gov ordered Proton to do some limited tracking for a specific user, after that they went to the court and succeeded in changing the law so it’s no longer possible to order this tracking.

Proton might not be ideal, but they seem to actually care about making the Internet a safer place.