Back Story and Flashbacks

What's the difference? That's a good question. One all writers need to understand. My writing buddy Claire defined the difference in the following way:
A flashback puts you in the head of the POV character at the time of the memory they're recalling; back story exposition keeps you in the head of the POV character now, as they look back and remember. Or as I like to think of it: flashbacks are active, they show an event from the past. Back story tells about the past. She's on to something that...