Is there any difference between champion colors?

I've been experimenting for a while with these "Champions". These are results of my observations:

• different colors have the same stats. I've found 3 Champion Frowning Gapers on the same level, each one of a different color. They did double damage(1 heart instead of half) and had approximately double health. They dropped a penny, a soul heart and a bomb.

• same color doesn't mean same loot. I've found, on the same playthrough, a red Charger and a red Vis. The first dropped a Tarot, the second a penny. In this same game though, I've dropped another Tarot, but this one from a grey Pacer.

Naturally these are only examples, I've done a lot more observations of this kind, but these seemed the most relevant.

The general feeling I got from these experiments is that the color is purely aesthetic. It looks like that a champion has Double HP + Double damage + guaranteed random drop (the drop is chosen between those indicated as "Pickup items" in the post already linked by Raven). Also the randomness seems to be confirmed by this Formspring post by McMillen himself: the drop is chosen at the moment of death, it's not predetermined.

Colored enemies are "rare spawns" (or "Champions", if you want to think in Diablo terms). They have a greater chance to drop items on death than their non-tinted brethren, but also have more damage and health.

Officially, this is known as "Champion Form".

Edmund, one of the devs, briefly discussed this in one of his development blogs.

Special enemies will be randomly colored, slightly larger then their brothers, do more damage and have more health.

The colored enemies ("Champions") are tougher, sometimes faster or having extra abilities. Two different colors will generally have the same abilities, but their drop will be different.

From what I have observed: there is no pattern, as this is random from every new game (Like the pills' effects, it's randomly selected at the beginning). But in a given play, if a green champion drops you a dime, then each subsequent green champion will drop you a "money" rewards.

The types of rewards:

• Money (Nickel, dime, possibly quarter ?)
• Health (Heart, half-heart, soul heart)
• Keys (Keys)
• Bombs (Bomb, 1+1 Free, Troll bomb)
• Activation item (Card, pill)