I'd say Immich has quite a few more features, with the primary focus of backing up your media from your mobile devices with a more "managed" approach (it takes care of storing and organizing the files).
Photofield is more minimalistic (both in terms of user interface and as an application) and more useful if you have an existing directory structure that you want to view as a gallery. It also pulls a few neat tricks to make it work smoothly with up to ~600k files.
See also the linked comparison for more details. It's mostly accurate, though video is a bit better with this release.
It's quite impressive how much the Immich folks have achieved in a relatively short period of time! I'm glad you found something that works for you :)