I have always been under the impression (though without actually trying) that chicharron was crispy fried pork cracklins.
I just came back from my favorite local Mexican deli where I'd decided to order a taco with this (instead of my usual carnitas.) I was expecting something very similar to carnitas, but lighter and crispier. Instead, I got a taco containing what appeared to be cubes of soft pork fat that seemed to have been stewed, rather than fried. It was tasty, but definitely not what I was expecting.
Have I been living a life of ignorance, did I simply encounter a regional variation, or are they crazy? I don't question the place's authenticity. (It was Tehuitzingo on 10th Ave in Manhattan for you NYers.)