system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are seas different from open ocean? Why do we name some swaths of water but not others?

This has been on my mind for a while, and I've never gotten a real answer. Why do we name seemingly arbitrary places in the water a sea? Are there any differences between the sea and another part of the ocean? Why are these artificial boundaries created?
gpt
We name all swaths of water. Locals will often name stock ponds and tanks. 

A sea is smaller than an ocean and separated/partially separated from it in some way. 

These boundaries are created like all boundaries are and are just as arbitrary. Boundaries show who owns what area, clarify the location you are talking about, and help general navigation.