I see the avengers is showing for imax 3D and 3D what is the difference of the two?

IMAX 3d theaters - A standard IMAX theater has a huge rectangular screen. A typical IMAX screen is 16 meters high by 22 meters wide (approximately52 by 72 feet), but they can be much larger. The largest IMAX screen is 30 meters (98 feet) high. Wherears standard 3d screens are the typical ones you see about 20-30 ft with 3 d

IMAX is a format. 3D is a capacity of that format. The filing was shot in IMAX, so instead viewing experience is with that. 3D is a "nice to have" on to of that but it's a matter of preference.