Privacy: I have blinds on my windows. I control whether they are open or closed, but they aren’t secure. You could break a window and look inside if you really wanted to.
Security: my glass storm door has a lock. But privacy is only there when I close the front door.
There is overlap between these two concepts but one does not imply the other.
They mutually imply one another.
If something was private, but not secure, well, that implies there are ways to breach the privacy, which isn’t very private at all.
If it’s secure, but not private, that implies it’s readable by someone other than the consenting conversational parties, which makes it insecure.
Privacy: I have blinds on my windows. I control whether they are open or closed, but they aren’t secure. You could break a window and look inside if you really wanted to.
Security: my glass storm door has a lock. But privacy is only there when I close the front door.
There is overlap between these two concepts but one does not imply the other.
…and proton advertises as both, which as pointed out, isn’t true