> Different neighborhoods.

not quite. the north side is the area north of the allegheny river (what historically made up allegheny city) and isn't a proper neighborhood in itself so much as it is a collection of city neighborhoods. north shore is one of those neighborhoods. you can kind of get away with calling some of the other areas along the northern side of the river "north shore" if you're not talking strict neighborhood boundaries, but they're all part of the north side.

so you're always in the northside if you're in north shore, but you're not always in north shore if you're in the north side.