My lovely friend Ricky put this out there and I think it pretty much sums it up. ;)

rickyv:

Dinner means you really want a relationship, a deal or both.

Lunch means you’d like to get to know someone to see if you want a relationship, a deal or both.

Breakfast means you’ve got a current deal to discuss (if you already have a relationship) or you’re willing to consider a relationship with someone new, but that person isn’t especially important.

Drinks are for friends or business people who have become friends.

Coffee is not even on the spectrum.

(from a good friend / scene veteran)