lol, big difference.

3D is,,, well, 3D is raddical manuevers performed in a condition where the wing is pretty much stalled and you are relying on the engines thrust to control attitude and altitude. The planes are usually over powered and have exaggerated control surface size and a very light wing load. Most advanced 3D pilots use scale aerobatic planes like the Extra, Edge, Yak, Sukhoi, Ultimate Biplane, Giles etc.. Lookup videos and you can see tons of 3D. The basic 3D posture is called the "harrier" position where the plane is flying with the mose up at about a 45-60 degree angle flying most on rudder control and engine thrust. The basic maneuvers are hovering and torque rolling, rolling harriers, High alpha knife edge flight and misc stalled spins. Examples of the spins are the Knife Edge Spin, upright and inverted flat spins, the "blender" and the "waterfall". Most good 3D pilots tempt fate by performing all of these maneuvers as low and slow as possible..
99% of really polished and well known 3D pilots cut their teeth on pattern flying, most fly pattern and IMAC. IMAC is basically pattern flying with the afforementioned scale aerobatic planes.

Pattern is a precise graceful sequence of geometric shapes that are performed in a particular order. "Pattern" pilot s must fly airplanes that are small enough to fit into a 2 meter square box and they must weigh less than 5KG or 11lbs. There are several different levels from "sportsman" to the world class level called FAI or F3A. The sequence and its maneuvers are scored on a scale of 0-10 according to geometric accuracy, roll rates, straight lines and overall symmetry of a manuever, generally speaking. Pattern is performed in a "box" that is indicated by lines extending out to the left and the right from the pilots feet at 60 degree angles. The box is also limited to a vertical limit of 60 degrees from the pilots point of view. Its all about geometry and disciplined control of the aircraft that required that the pilot is able to put the plane EXACTLY where he wants it when he wants it to be there.

These are my planes. The blue one is for 3D/IMAC and the pink and yellow one is my pattern plane.