(Ask) what is the the difference between a light novel and a regular ol' novel?

I’m not too sure myself, actually? According to most definitions I saw online, light novels are a style of japanese novel that are generally supposed to be lighter in content, easy to read, and not all that long, but some SAO LNs have over 300 pages? Light novels also generally have some illustrations, I guess. 

From my understanding they are supposed to be something akin to american pulp novels and generally aimed at younger audiences, but that doesn’t seem to be true to all LNs?