damage to the skin can temporarily disrupt or permanently destroy pigment production in the skin, creating white scars

• pinto is the most common AmE term for these wider leucistic patterns (from the Spanish word for “painted”)
• BrE equivalents would be pied (from resemblance to the magpie bird), and its derivates piebald (pied black) and skewbald (any other pied colour)
• spotted is used for leucistic patterns but only in the US (as in Spotted Saddle Horse). In GB it means Leopard Complex patterned (as in British Spotted Pony).
• coloured is sometimes also used in this way, which makes me absurdly crave murder (e.g. Coloured Horse And Pony Society of UK)
• blagdon is a special, special term that’s used for Irish/Gypsy/Coloured/Tinker Cob/Vanner/Horse those majesticc thicc manetasticc bois, that are not “normal” pied (Tobiano) but also not “solid” (having white markings limited to the face and the lower legs) – having extra tall stockings, white belly spots, plenty of intermixed white hair on the body, that sort of thing
• the Paint, or more properly the Paint Horse is a cattle horse breed that is expected to have a leucistic pinto/pied pattern – “paint” is often (but incorrectly) used synonymously to “pinto”
• Tobiano is the name of probably the most common specific leucistic pattern with its unique look. It’s usually obviously pinto/pied and rarely suppressed enough to look solid.
• overo is a colloquial catch-all term for all pinto patterns other than Tobiano. It’s also used as the shorthand name for the specific non-Tobiano pattern more commonly known as Frame Overo (for how the pattern usually looks like) or Lethal White Overo (for the fact the mutation that produces the pattern, when inherited from both parents, makes all-white foals with terminally borked intestines)
• other distinct types of non-tobiano-leucistic-spotting are Splashed White, Sabino, and Dominant White (although the distinction between the latter two is arbitrary, and not nearly all “Dominant White” mutations act dominant or produce all-white coats…)

• Appaloosa is a breed of horse that is expected to show a Leopard Complex coat pattern. Some of these patterns are leucistic, others not. The breed’s name comes from the name of a river in the region where the Niimíipuu tribe, original breeders of these horses, lived
• Because the Leopard Complex patterns are, well, complex, and went out of fashion for centuries in Europe, there is no well established English name for them. Hence, “appaloosa” is also used particularly in the US as a generic name for the colouration the Appaloosa breed is known for.

• Tobano, Overo, Appaloosa, Pinto, Paint, etc… are all patterns of never-pigmented skin under white hairs.
• Gray horses look white, but their skin remains pigmented. Think of a human with grey hair.
• Vitiligo in ponies is both over time, like graying out, and is a depigmentation of the underlying skin.