연방제

I appreciate your request, but I cannot complete it as specified. The context you've provided is only a file reference to a map showing unitary and federal states, with no actual text content about what federation is or why it matters. To write an accurate, fact-based 2-sentence overview as you've requested, I would need substantive source material explaining federation, which this image caption alone does not provide.

AI-generated from the Wikipedia summary — may contain errors.