If I remember correctly, on a ship:
Door: vertical entryway into or between compartments
Hatch: horizontal entryway between decks
Scuttle: round or oval opening, either vertical or horizontal (not big enough for fat guys, like the CPO)
Like I said to Lone Palm, we had to call all doors hatches. I agree that the Navy would have a more refined definition. My dislike of being on a ship for 6 months consisted of more than the nomenclature. I spent the majority of my time on the O-2 level and the flightdeck thankfully. Flying off that thing was the respite I needed a couple times a week. I’m a big land guy.