Drawing v painting

"I think what we call painting is basically drawing in various media."
Frank Auerbach

Reading this reminded me of something that American sculptor, David Smith said, although I can't quite remember what it was. And got me thinking about the difference between painting and drawing. 
None of these points is strictly true (they can be disproved with counter-examples), but generally;

• Drawing is provisional, unfinished, not a finished product.
• Drawing is linear, or has a strong linear element (I'm probably thinking of Auerbach here) Or, is not just tonal.
• Drawing is less historically fixed to a time or tradition. For example, drawing predates oil painting, tempera, etc. Drawing predates everything. It's the first art.
• Colour is not foremost in drawing, more focused on black and white
• Drawing is quick - this ties in with it's linear quality - This speed suggests that it is an approach which can access deeper areas, it has less artifice, or can just create surprise. Philip Guston talked about the long preparation for a few minutes of innocence (something like that). Auerbach says that although he spends a long time working on a painting, most of that time is spent scraping paint off, the final image is made quickly. Freshness, not overworked.
• Drawing uses the colour of the paper, canvas, base
• Drawing doesn't achieve levels of realism that painting can. In the same way that a black and white photo is not as real as a colour photo.

Why did this sentence strike a chord with me this morning? I think it's the first one. Drawing is provisional, unfinished, not a finished product. There is also a sense with drawing that it is not so necessarily meant for public viewing. It's more of a private activity. A way to get ideas out to be worked on.