Sea bus vs ferry – what's the difference?

Şehir Hatları are the classic city ferries with outside decks. Sea buses (deniz otobüsü) are faster catamarans, enclosed, used for longer routes like Bursa or the islands. For sightseeing pick the classic ferry.

Classic ferries have tea sellers, best part.

Turyol and Dentur are smaller private boats on some routes.

All take Istanbulkart mostly.