In Japan, it is common to add “+x” to the end of an album’s title when reissuing an album with bonus tracks, where x is the amount of bonus tracks. Example: https://musicbrainz.org/release/f19b2666-1330-4c73-8606-06495106f12f
I personally think this should be part of the disambiguation, but others disagree and there does not appear to be a settled rule here.
The reason I think this belongs as a disambiguation comment is because I see this as something like “with bonus tracks” rather than a meaningful stylistic change to the album’s title. It’s often noted on the obi strip or side rather than on the front cover.