Upper Peninsula vs Upper Peninsula of Michigan

Upper Peninsula and Upper Peninsula of Michigan both are nouns.

Word	Noun	Adjective	Verb	Adverb
Upper Peninsula	Yes	No	No	No
Upper Peninsula of Michigan	Yes	No	No	No

As nouns, Upper Peninsula and Upper Peninsula of Michigan are synonyms defined as:

Upper Peninsula and Upper Peninsula of Michigan: the peninsula between Lake Superior and Lake Michigan that forms the northwestern part of Michigan

Upper Peninsula (noun)	Upper Peninsula of Michigan (noun)
the peninsula between Lake Superior and Lake Michigan that forms the northwestern part of Michigan	the peninsula between Lake Superior and Lake Michigan that forms the northwestern part of Michigan