As I pointed out on another thread, sedeprivationism is NOT strictly sedevacantism. In fact, Father Ringrose emphasizes that point.
SEDEPLENISM -- See is occupied simpliciter.
SEDEVACANTISM -- See is vacant simpliciter.
SEDEPRIVATIONISM -- See is occupied secundum quid and See is vacant secundum quid.
SEDEIMPOUNDISM -- See is occupied secundum quid and See is vacant secundum quid.
What's interesting is that certain SEDEPRIVATIONISTS, like +Sanborn, will EMPHASIZE the vacancy part, while others, like Father Ringrose, will emphasize the occupancy part. So the difference is merely a matter of emphasis.
Father Chazal opts to put SEDEPRIVATIONISM under SEDEVACANTISM, but that's not strictly true. It's actually in between the two somewhere ... just as his own SEDEIMPOUNDISM is.