what is the difference between "waterless cooking" and "pressure
cooking"? Waterless cookware design clearly differs from
pressure-cookers...yet the ideas seem absurdly similar. This would
lead me to believe the difference is not only a matter of design, but
idealogy towards cooking. Thus the methodolgies are similar, but
differing on key points. In this case the question would have to be:
What are the arguments for or against each percise methodology...and
what are the methodologies, exactly? I can say more if necessary.

Pressure cooking was simply an old fad that has had its day.

New methods come along from time to time but who cares as long as the
stuff is cooked to perfection?

If you have got one of those Swiss gizmos that look like pressure cookers
- then it is 'steam versus pressure cooking'

- not exactly waterless

- do not drink and cook with those things

"Waterless" cooking is the same as baking, but you are not releasing
any of the water vapor into the atmosphere, losing it, and dehydrating
the product as much.  You might "scorch" a few items, but if you cook
at a low enough temp, you'll be fine, but you will notice some
structural changes in the food.

Steam cooking is fine too.  Just don't use a lot of water in the
bottom of the pan.  Example:  Boiling vegetables simply heat treats
them for safety, but it also dilutes the precious vitamins in the
vegetables into your water.

There are too many variables in how food is cooked in general.  You'll
just have to try either method with each item.