Briefly looking at the files and code it's hard to tell whether that is still the case, but it's fair to assume Import-Export would reuse most of the machinery behind Bridge.
bridge exposes imap making it easy to download all your data using Thunderbird or another client. I don't know about "export" because imap does what I want and is supported by most providers in the same format.
For those who care about OSS and moving to Protonmail from bigcorps email, this _might_ matter, although I think that for the majority of Protonmail users (which doesn't care much about open source), it doesn't matter.
The repository for Proton Mail Bridge (which is open source) claims to also host the source for the Import Export app.
Here: https://github.com/ProtonMail/proton-bridge
Briefly looking at the files and code it's hard to tell whether that is still the case, but it's fair to assume Import-Export would reuse most of the machinery behind Bridge.
bridge exposes imap making it easy to download all your data using Thunderbird or another client. I don't know about "export" because imap does what I want and is supported by most providers in the same format.
Does it - legally - matter?
For those who care about OSS and moving to Protonmail from bigcorps email, this _might_ matter, although I think that for the majority of Protonmail users (which doesn't care much about open source), it doesn't matter.