Flipping is what happens when you accidentally trip over your partners' tacklebox en route to falling overboard.
Pitching is what happens when you get back on board and intentially throw your partner overboard for placing said tacklebox in your way!
Subtle indeed, but I hope that clears things up for you!
Oh Alright!! Lessee if I can tackle this one.
I just first want to say it's best to SHOW rather than describe the techniques, but here goes...
Flipping is the technique of placing a lure in a given spot at close range (0-10') precisely, and quietly, with as little disturbance of the water as possible using an underhand pendulum cast while controlling the line with your hand.
Pitching is the technique in which worms or jigs are dropped into cover at close range (5-20') with an underhand pendulum motion, using a 6 1/2 to 71/2 foot baitcasting rod. Similar to flipping, but requires less stealth and usually done from further distances.
Both techniques allow you to place a bait precisely into a pocket or under tree limbs without spooking bass. These are best suited when bass are buried deep in cover such as brush, downed trees, heavy weeds and such when conventional casts will not get the lure to the bass.
There's more information at
http://www.bassresource.com/html/flip&pitch.html with links on the bottom to even further detailed info.
Hope that helps!