In practice, it probably wouldn't be. Same way as a Facebook or X/Twitter plugin wouldn't be different than Generic OAuth. The differences here would be that it would have a reduced number of fields for the user, since a lot of the answers are already known. But for the most part, all of the built in providers would end up using the same pathway as the generic oauth provider.
For Wordpress specifically, I imagine either it would not be directly supported (generic oauth only) or it would be designed to work with the most popular plugins.
For the SQL provider, it just does what the standard login provider would do but refers to a different database/table than the standard XenForo database. I'm honestly not sure of when/why this would be useful as I've never used it myself, but someone may have an idea of how to use this.
As for LDAP, there wouldn't be any redirect. It would work similarly to XenForo's native login provider, but instead of consulting the database it would make an LDAP call to the configured server and either get a token or an access denied back.
Effectively yes.
