There was a multi-page discussion about this about a year or so ago. You may do a search and find it. I was the original poster, but if memory serves me right, it got nasty and had to be locked. Try PMing Jeff Horton about it. He has some good insight into the differences.
I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"