It would be more proper to talk about the Navy as a whole as a subculture with social stratification as one of its aspects.
Social stratification is one of the aspects of the Navy as a subculture. There are major differences between people of different ranks. This is particularly true between the officer corps and the enlisted personnel. This difference is upheld both by tradition and by regulation.
However, social stratification is not the only characteristic of this subculture. There are also differentiations (sub-subcultures, if you will) between people who hold specialized positions in the Navy. Pilots and submariners would be good examples of these.
There is also a set of attitudes that tend to be different from those of the American populace as a whole. These include things like more conservative political leanings and a strong sense of being different and perhaps special because of their military service.