What are security features of their VPN or email that are not in other VPNs or emails, that I can measure? I.e. I don't care how military grade is their server

What are security features of their VPN or email that are not in other VPNs or emails, that I can measure? I.e. I don't care how military grade is their server side encryption or I don't care that they decrypt in my JS, as long as threat model remains the same. What they changed in the model? Is it trustless?