Egg corn vs Mondegreen

I've long been a connoisseur of mondegreens. Only more recently have I become aware of a devilishly similar term, eggcorn. I just spent 15 minutes researching the compare-and-contrast, and I am not sure this is settled law. My quick take: Mondegreens completely alter the meaning of the phrase, while eggcorns keep it at least adjacent (chomping at the bit vs champing at the bit).

Some sources claim that mondegreens are distinguished by a nonsensical meaning, but I think that is a side-effect, not the main effect. I.e., very often the completely different meaning will be off-the-wall, but not always. In fact, the founding mondegreen changes the meaning substantially, but in an entirely sensible way.