Update: synonyms were added. Thanks to everyone who voted
Considering that the tag multiple-monitors has 3096 questions tagged right now, we may want to make all of those synonyms of this tag.
Back to the topic.Ubuntu Wiki articule and Arch Wiki article on this topic use "Multihead" and "multi-monitor" terminology. Gentoo Wiki as well. So these two are ...
Judging from the comments and upvotes on the question, I've taken a liberty to untag all the questions that were previously tagged with [comparison]. Currently, there is one remaining post that is locked by moderator so I could not edit that out. Otherwise, the tag is ready for deletion
Update: the tag is deleted