Yes, the 200S cabinet was made earlier. It was the cabinet made to go with the 200S amp. In fact, they were sold as a set. This was in the late sixties.
The 215S came out in the early seventies, when Sunn went to a mix'n'match philosophy. Pick the head you want, pick the speaker cabinet you want. The 'S' designation meant it was simply a speaker, not designated for either guitar or bass. Other cabinets were of the folded horn design, and had an 'H' designation. these were meant for bass and low frequency PA use. Later cabinets had 'B' and 'L' designations, for obvious reasons.