The size and structure of the horses’ bodies is the most visible distinction between domestic and wild horses.
Although several breeds have sizes that are comparable to those of wild horses, there is a far wider range of sizes, from the smallest Falabella to the largest Shire.
In addition to their larger size, you might also note that wild horses’ manes stick erect in contrast to domestic horses’ that flop over. The coats of domestic horses are smoother.