In reply to Display fonts vs text fonts- Arbitrary designations?:
After thinking about it further, you are right. I was not considering readability, which is indeed something different than merely being able to distinguish what something says, particularly in brief. I will spend some time comparing various serif fonts that I do have, with extended reading, to see how readability varies. It's unfortunate that book publishers rarely if ever name the font used in books. It would be great to be able to just pull them off the shelf and see what's what.
On another front, I did observe the main differences between a text and display font, and it was as David indicated. I opened up two fonts.com windows side by side with sample text from the same font and size, one being display and the other being text. The characters themselves appeared identical, but the spacing between words is indeed smaller, and so is the spacing between lines.