Here's a breakdown:
Chestnut:
* Body: Reddish-brown to golden.
* Mane and Tail: Same color as the body, with a slight tendency towards a reddish hue.
* Legs: Matching the body color, sometimes with slight black markings around the hooves.
* No Black: A chestnut horse will never have any black markings except for maybe a tiny black patch on the muzzle.
Bay:
* Body: Ranges from a light reddish-brown to a rich brown.
* Mane and Tail: Black.
* Legs: Black, sometimes with white markings.
* Black Points: Black markings on the face (muzzle, around the eyes, ears) and legs.
Key Differences:
* Black Points: The most noticeable difference is the presence of black points on a bay horse, which are absent on a chestnut.
* Mane and Tail: A bay horse has a black mane and tail, while a chestnut horse has the same color mane and tail as its body.
Important Note:
* Color Intensity: Both chestnut and bay horses can vary in their shade of red or brown, from light to dark.
* Dilutions: There are also variations within these colors, such as "flaxen" chestnuts (with a blonde mane and tail) and "liver chestnut" (very dark brown).
Ultimately, the distinction between a chestnut and bay colt is determined by the presence or absence of black points and the color of the mane and tail.