He is talking about the raw hides. In other words, the fresh skin off of a cow or horse.
Post tanning, they become visually pretty much identical. In fact, this was the basis for a scandal in which an unscrupulous seller was selling horsehide as a premium upgrade, then selling cowhide anyway despite the upcharge. This was obviously an act of fraud, however it is telling that so many people with wide jacket and leather collections couldn't tell the difference…
On the contrary, the minor differences between cow and horse hide, if visually apparent at all, only become so as the jacket is worn in and the leather develops break.
Deer, goat, and sheep hides are completely distinct from horse and cow. Those two in particular are nigh-indistinguishable. You're introducing irrelevant things here to obfuscate this point.
I mean I could double down with you that I can tell the difference between stingray or crocodile leather and cowhide. Sure. That doesn't say anything about cow v horse in particular.