Eight finishes, and they are not variations on a theme — the dial texture changes completely between them. A Jupiter dial and a blue Earth dial are recognisably the same watch and a totally different object on the wrist. Here is how they actually differ.
The loud ones
Orange / Red Planet. Orange silicone, a red-amber planet, steel case. The most extrovert of the set by a distance. In daylight the dial reads almost molten. If you are buying the P6676 because you want it noticed, this is the one.
Black / Jupiter. The banded tan dial is the most literally planetary of the eight — you can read the storm bands across it. Black strap keeps it from tipping into costume.
White / Mars. Red-brown dial on a white strap. Unusual combination, and the one people ask about most.
The everyday ones
Black / Blue Planet and Black / Blue Earth. Both pair a black case and strap with a deep blue dial; the Planet is a smoother sphere, the Earth carries more visible continent-like texture. These are the two that pass as a normal watch from a metre away and reveal themselves up close.
Blue / Gold Earth. Blue strap, blue-and-gold dial. Warmer than the black versions and the easiest of the bright options to wear daily.
The quiet ones
White / Gold Moon and White / Black Moon. Lunar greys rather than planetary colour, on white straps. Lowest contrast of the eight and the closest the P6676 gets to restrained — the Black Moon in particular reads almost monochrome until light hits the dome.
Which should you actually pick?
If it is your first planet dial, one of the black-strap blues. They carry the effect without committing you to explaining the watch every day, and black silicone goes with everything.
If you already own something loud and want a second, take the Orange or the Jupiter — buying a quiet version of a deliberately bold watch tends to end in a drawer.
Does the colour change anything mechanically?
No. All eight share the same 48mm case, curved crystal, Miyota 8215 automatic and 50m water resistance. The choice is purely how loud you want it — the full review covers the specification in detail, and planet dials explained covers why the domed construction looks the way it does.