I would like to compare a std CD in my library against the Tidal equivalent, am I right that if the album is in my library it won’t show as a selectable album in Tidal ?
If the CD is already in your library, go to that CD. Choose the 3 dot menu at the top, marked 1 in the pic below, and then choose Go To Tidal Version. You can add tracks from both to your Queue and then quickly A/B them in the queue.