Three of those are "speedboats" (these sorts of things: https://en.wikipedia.org/wiki/Ashura-class_speedboat), and one's a "gunboat".

Only one of the five vessels (the frigate) lost would typically be called a "ship".

Yeah. It also says that the US showed mercy after hitting the other frigate with a 500lb bomb and allowed it to limp away. They've edited their post- they originally claimed Iran had two ships in their navy.