Project owners or support officers may often need to distinguish users that have interacted in some way with a feedback item (commented, voted) to those that have said that want to follow it.
Subscriber is a person who has had any interaction with the feedback item (creator, follower, commentor, voter, etc.).
Followers are subset of subscribers. The users that have explicitly stated that want to follow the item, and have "Following this item" button active
Followers could be exported from Actions menu - for a single or multiple items selected, or from the followers window of the feedback