Correct. The feature matrix is pretty complicated between Unleashed, ZD, SZ, and standalone. Unleashed manuals only compare Unleashed vs ZD, making these answers (unleashed vs standalone) harder to answer.
Many Standalone AP users will employ an external HotSpot authentication server with their own custom Login page. Many Standalone APs can point to this same HotSpot server.
Unleashed allows multiple APs to communicate with similar to ZD functionality (including Guest Access).