Hello. I thought I could use my Lemmy login details to log into PieFed, but it isn't working and had to create a separate account. Can you please clarify?

separate account is normal

the content (communities/posts/comments/votes) is accessible from any server, but the logins/passwords are not

It would be nice if we had something like friendica but VERY hard to implement.

Piefed is different software to Lemmy. The instances are different.

That answers my question. Thank you

Can one set up an account on one friendica instance and log in with it into another?

the content (communities/posts/comments/votes) is accessible from any server*

*As long as your instance is federated with the instance where the content is, and does not block the community.

I would love for the fediverse to work that way but it does not. I really with they would have started with login servers that were seperate from community servers and allowed for a kind of saml type interaction.

I believe so. They had some sort of system setup if i recall.

It doesn't depend on fediverse software.

Whatever is the fediverse software, your credential will only work on your instance, your fediverse home server.

More exactly, your credentials are stored in the database of a server. If you have created an account on lemmy.world, you can't login on lemmy.zip (another server), nor mastodon.social (another server...), nor peertube.org, loops.xyz...

Because they are different server, they don't share the same database, they have their own database.
Your credentials are only on lemmy.world, so other servers don't know who you are.

However, there are several technical solutions, that allow cross-platform login. They are not easy to set up :

LADP

We could create a LADP, that's a huge database with users credentials. For example, yunohost. When you install several apps with yunohost, you don't have to create another account for each installed apps because those apps share the same database where your credentials are stored.

OAuth

There is another method : OAuth. I guess it talks with severs but i can't explain how it works. Piefed use it for login with already existing account elsewhere as mastodon (?). We could log in to piefed with a mastodon account, or google.

Different services from different groups that just allow talking with each other, like emailing a Protonmail user from a Gmail account.

To OP, however you can import your settings from your Lemmy account. Its not gonna your copy posts or comments but blocklists(blacklisted users/communities/instances) and subscriptions.

That's very helpful and clearly explains how it works. Thank you, much appreciated.