It Depends! In my experience - some are extra intervals, some are just longer. It can go the other way too, with minus versions shorter with the same interval durations, just less recovery (so a higher intensity).
Then there’s the minus versions that are the same length, but different intensity. I think there’s a few sweet spot minus versions that split intervals with a short break in between for example, and plenty of VO2 Max ones where percentage above FTP varies or interval duration, but workout duration is the same.
After taking a hammering on some plus 1 versions when I’ve had more time, I now generally use the extend cooldown feature and ramp up the intensity (for the cooldown) if I want to add extra duration/ TSS.