The third bulb is the Reveal LED. It blocks a little bit of light from the yellow part of the spectrum from escaping the bulbs -- this helps it make the colors in your home look more vivid, but it also means that the Reveal LED is a bit less bright than its brethren.
Compare the Reveal LED's light to this 60-watt incandescent on the left. The Reveal LED produces cleaner whites thanks to the muted yellow tones, but that also means it produces yellows that are less saturated.
GE's HD Light LEDs start at $8 for a two-pack of Relax bulbs, with two packs of the Refresh and Reveal LEDs selling for $9 and $10, respectively. Check out our full GE 60-watt Equivalent HD Light LED review for all of the pros and cons.