Thanks to Marine Insight for this:
A ship has a number of different types of decks which are located at different levels and places on the ship. Needless to say, every seafarer should be familiar with the various types of decks.
10 Types of Decks Every Seafarer Should Know
1. Poop Deck: Originating from the Latin term for a vessel’s stern-side – Puppis – the poop deck is located on the vessel’s stern. The poop deck is basically used by the vessel’s commanding superiors to observe the work and navigational proceedings. Technically, it is the deck that forms the roof of a cabin built in the aft part of the superstructure of the ship.
2. Main Deck: As the name suggests, the main deck is the primary deck in any vessel. The main deck however is not the topmost deck in a vessel which is referred to as the weather deck. On sailing warships, it is usually the deck below the upper deck.
3. Upper Deck: The deck that covers the hull of the vessel from its fore to its aft is the upper deck. It is the topmost deck on a ship. In all vessels, the upper deck is the biggest deck amongst all other decks.
4. Lower Deck: The deck located below the primary or main deck is the lower deck. Generally, the lower deck comprises more than one deck. It is just next to the lowest or orlop deck.
5. Promenade Deck: Promenade refers to taking a lazy stroll in a feasible place like a beach or a park. In a vessel, the promenade deck serves as a place for the voyagers to take a calming and enjoyable walk on the ship while enjoying the beauty of the oceanic vista. It is generally the area around the superstructure. It can have open railings or can be enclosed in a glass.
6. Tween Deck: ‘’tween’ is a colloquial abridging of the word ‘between.’ In a ship, the tween deck actually means an empty space separating or between (tween) two other decks in the hull of a vessel.
7. Flush Deck: The deck that extends without any constructional breaks from the frontal part of the ship to the aft is referred to as the flush deck. On such decks, there is no raised forecastle or lowered quarterdeck.
8. Weather Deck: A deck that is not roofed and thus is open to the ever-changing weather conditions of the sea is referred to as the weather deck. It is the uppermost deck on the ship which is exposed to the environment.
9. Bridge Deck: Bridge deck is the deck on which the navigational equipment of the ships are housed. The skipper and the rest of his commanding officers generally are positioned on this deck during the vessel’s voyage. It is the room or a platform from which the ship is commanded.
10. Quarter Deck: The deck located near to the chief mast of a vessel on its stern is referred to as the quarter deck. The quarter deck is a part of the upper deck and is inclusive of the poop deck. The quarter deck is generally found on navy ships and accessible only to the most senior naval officers on the vessel. When in port, all the activities of the ships are controlled from the quarter deck.