RE: noodle rod-drift rod ?
action and power are the differences. A true noodle rod is ultra light power and slow action. You can bend it into a complete C shape pretty easily. They are normally rated up to 6 lb line, though I've seen some rated for 8 lb. A true noodle is designed for light line and light baits like single eggs, flies, and tiny jigs.
A drift rod is designed to drift larger baits, usually along the bottom. A normal drift rod will be rated 4-10 or 6-12 line and have a lot more power a lot higher into the rod. You'll get a bit faster action most of the time.
That said, many of the rods being called noodle rods have too much power to be a true noodle rod. Some of the drift rods are being pushed into noodle territory. The 9' 4-8 lb St Croix wild river is a drift rod, but a very light one. Makes for a great spoon casting rod and bank full bait rod. It fishes great with a chunk of skein in the mouths too. Not light enough to throw single eggs all day though.