What exactly does "Hospital Grade" mean?

I plan on changing my outlets since it seems like a cheap enough tweak and most here on the forum agree that it makes a difference. But what actually IS the physical difference between hospital grade and non-hospital grade outlets?
It means that someone has been clever enough to charge audiopiles who don't know anything about electricity a ton of money for -- wire.
Follow Up
"Next I tried The HBL8300. Imho the plug pushed in harder and pulled out harder. Is it due strictly to the Hot and Neutral contacts or is it due to the hosp grade ground connector???"
I did not want to leave the impression that the difference in tightness was due to the ground prong, it was not. I did try the test with a two wire cord and plug also....

>>"It means that someone has been clever enough to charge audiopiles who don't know anything about electricity a ton of money for -- wire.'<<

Bojack did read page 2 of the link I provided.
What nomenclature did Robert read claiming that hospital grade outlets are guaranteed spark free in the Stereophile article? How can this be true?
Nerspellsner, I found a few errors in the Stereophile article.

Besides that one you mentioned,

The Hubbell HBL8300I receptacle. The I does not stand for plated, it stands for ivory.

The picture of the two outlets, the top outlet sure looks to me to be the non nickel plated Hubbell HBL8300H, not the plated HBL8300.

On the whole they did a pretty good job with the article for being laymen when it comes to electrical.
Studioray, I installed the Hubbell 5362 outlets for my ARC VT50 power amp and my Sonic Frontiers Line One preamp. Plugged things back in and turned the system on. Right off I could hear a difference. As I have read from others the bass was deeper. I first started with a Female vocal and did notice siblence sounds, the dreaded sss sss. I was hoping that was due to the fact the outlets were new and needed some break-in time. For lack of anything else I could think of to plug into the two outlets and let them cook for about 24 hours, I used two table lamps with 3 way bulbs. I turned the switches on the lamps to the highest wattage. Tonight I unplugged the lamps and plugged back in the equipment. Turned things on, let the system warm up for about a half hour and sat down for a listen. Siblence were gone. The bass from my system is deeper. The sound is darker, sound stage more layered. The Hubbell 5362 beats the Leviton Hospital Grade outlets hands down. It has to be that steel supporting yoke,strap. Or maybe the Hubbell is more dampened.

I still have to change the outlet for the CDP, one thing at a time.

And then there is the outlet cover plates. I am presently using the Leviton magnetic Stainless steel plates with a nylon trim screw. I know Nerspellsner, I am guilty, busted!
This weekend I will experiment with the nylon outlet cover plates.

Also I am Still going to try the Hubbell 8300H Hosp Grade duplex outlets. I just need to make up my mind whether I am going to buy the Cyroed outlets.

Studioray, You did not mention in your thread if you have dedicated audio branch circuits.