I hear those two words (bay / creek) used together, and sometimes interchangably, all the time. They're (technically) not the same thing ... though they can be "combined" (existing together).
We all pretty much know what a "creek" is .... as they're usually a source of running water (or once were). A "bay", on the other hand, may or may not have a creek running into it ... or even having been formed by a creek. The definition of a bay is : A body of water partially enclosed by land, but with a wide mouth, affording access (to the main body of water).
Cove, on the other hand, is defined as a "small sheltered bay in the shoreline (of a larger body of water). A "pocket" would be an even smaller indentation in the shoreline, I guess.

That's the way I see it, therefore the way I describe it ... when relating information about location or types of topographical lake structure.

... pappy