1976 was the Bicentennial year, so they struck the quarter, half dollar, and Ike dollar with special reverses and dual dates on the obverses. When they returned to striking the old design, Krause felt the need to put an "A" in front of the old catalog designation (go figure).
Are we talking about the bold and thin letters? We like to call the bold square T's. And the thin letters slant T's
Bold T square T Thin letters, slant T's
To me the easiest way to tell is to look at the T's in states. The bold as square ends on the T's. And the thin letters have a slanted end on the T's.