Digital BW, The Print

Reading an old thread on levels and grain I had some questions...

Regarding the difference between levels and curves... aren't they doing exactly the 
same thing, just with different interfaces?  Additionally, curves gives you more 
flexibility than levels (although levels has some features curves doesn't)... but, the end 
result as far as the manipulation that is done to the image is identical.  So, one should 
not be "better" than the other WRT image degradation and grain.

So if I was to put a quantitative number to the amount of contrast I need to add to an 
image... lets say 20 points of contrast (whatever that may be).  If I add 20 points of 
contrast on an image using levels and 20 points of contrast in curves on a copy of the 
same image, one image isn't going to be less degraded or less grainy because I used 
curves instead of levels.

Am I correct on this?  This is why I'm not sure I understand why people say levels is 
more destructive and causes more grain than curves.

Shouldn't the main point be to have as much contrast or do as much manipulation in 
levels or curves, making sure not to clip information unnecessarily?

Jeff
http://www.jeffsingerphotography.com