An eggcorn and a mondegreen are both types of linguistic errors, but there is a difference between them.
An eggcorn occurs when a word or phrase is changed to another similar- or identical-sounding word or phrase. Even though eggcorns are erroneous, they are logically possible (e.g., mixing up “acorn” with “eggcorn” or “death knell” with “death nail”).
A mondegreen occurs when we unintentionally mishear a word or phrase in a poem or song lyric (e.g., mishearing “I wear goggles when you are not near” instead of “My world crumbles when you are not near”).
In short, both eggcorns and mondegreens involve misunderstanding language, but mondegreens are sp