I think the core difference here is that with graphene you use (if you want to) the google play services from google, but with very different security (iirc it

I think the core difference here is that with graphene you use (if you want to) the google play services from google, but with very different security (iirc it runs like a regular app, without special access to the system). But /e/ (horrible name btw) uses microG, which aims to replace parts of the google play infrastructure (but still relies on google servers afaik)