These two pieces can be difficult to tell apart. The difference is clearly shown in the 1930-34 NCC Cambridge catalog p. 129.
Top: 12 oz. goblet, height 6-1/8". Note longer stem. Courtesy of McCann's - Always Available Antiques.
Bottom: 12 oz. footed tumbler, height 6"; opening 3-7/16"; foot 3-1/16. Also shown in the thumbnail. (Replacements calls it an Ice Tea.) Courtesy of Norman Ketchie.
This line may be found plain, engraved or etched. Colors: Amethyst and many of Cambridge's other transparent colors. Note: This line is often confused with Morgantown's Golfball line and to a lesser extent Fry water goblets with a similar stem.