It’s kind of hard to see, but the 2007 coin has a capital ‘U’ in ‘UNITED STATES...’ while the 2008 coin has a little tail on the ‘u’ for the same word. The reason it’s hard to see is that the size of the ‘u’ remains as big as the ‘N’ beside it. Hope that helps.
Wow. In a million years I probably would not have noticed that.
Very good find.
Your sure it’s not in the literature? How did you find it?