For starters, James Webb's field of view will be significantly larger than the camera on the Hubble telescope . Its resolution will also be much better even than the Spitzer infrared space telescope .
It is much larger than Hubble. James Webb's primary mirror is nearly three times as large as Hubble's. In total, it is almost twice as large as the Hubble telescope, which is 13 meters long . Only its base measures 22x12 meters. Of course, it weighs half that of Hubble.
Hubble orbits the Earth (in a close orbit) and James Webb will orbit the Sun, so it will fly up to 1.5 million kilometers from our planet.
Webb will primarily view the universe in the infrared spectrum, while Hubble will primarily view it at ultraviolet and optical wavelengths. In addition, its four scientific instruments to capture images and spectra of astronomical objects, will provide a wavelength coverage of 0.6 to 28 micrometers. Hubble's instruments can observe a small portion of the infrared spectrum from 0.8 to 2.5 microns, but their main capabilities are in the ultraviolet and visible parts of the 0.1 to 0.8 micron spectrum.