Exactly. A "yuper" is someone from the U.P.

The state is, geographically and economically speaking, divided into three parts: downstate is the lower half of the lower peninsula, which is heavily populated and is the center of manufacturing and government; up north is the upper half of the lower peninsula, which is mostly agricultural and recreational; and the UP, the whole of the upper peninsula, which has extraction industries such as lumber, mining, and hunting. The only point at which the two peninsulas meet is the Mackinac (pronounced Mak-i-naw) Bridge, a 5-mile long suspension bridge over the straits between Lake Michigan and Lake Huron. In these parts, we speak of "the bridge" without further need to identify which one.

There are a lot of tourists in the up north area, especially in the summer, and especially in the Traverse City area on the west side of the lower peninsula. For whatever reason, there is a fudge shop on every corner of the tourist-trap towns in that area, and many of the tourists walk around carrying boxes of newly purchased fudge. A "fudgie" is a tourist or new resident of the area (defined as anyone who hasn't lived in the area for at least 20 years).

To a yuper, a "troll" is anyone who resides in the lower peninsula: a troll lives under the bridge.