Are bi-directional links and tags case sensitive?
Yes and no.
Technically both tags and references are case sensitive. Even more so they are unique for each rem: You can have two different tags/references to two distinct rem with the same name (at different places in the hierarchy), because tags/references are actually based on the target rem id and not the text of that rem. (This way you can also reference rem without text like images if you Tab to it using the hierarchical search.)
[[ searches which you use to add a tag or reference on the other hand are not case sensitive.
Thanks for answering.
What are best practices for using a reference vs a tag? They seem the same to me except with a tag you can link ideas without having to include the actual tag name in the content. With a reference the link is part of the content.