Fascists and Anarcho-Capitalists have certain abstract philosophical differences, but in practice, their actual behaviors are almost identical. Most (Fascists|Anarcho-Capitalists) are young, white males who use the internet way too much and either don't vote, or vote Republican. Even among their intellectuals, there's a lot more overlap than you would assume: https://en.wikipedia.org/wiki/Hans-Hermann_Hoppe.

The left-rights spectrum isn't supposed to capture the details of everyone's ideology: a spectrum that did that would be some kind of 20-dimensional hypercube. It's just supposed to capture who take who's side when it comes to that.