Here, we are looking at the exact same galaxy, known as NGC 3627 (also known as Messier 66), in both images. The image on the left shows the galaxy as it appears at optical wavelengths, which gives us an opportunity to see the various star forming regions scattered about the galaxies dust lanes (they, in turn, comprise the majestic spiral arms). In the image on the right, we are looking at a composite, stitched together using archive data collected of the galaxy at multiple wavelengths.
From these wavelengths, we are able to see activity going on that would not be visible otherwise. Particularly, we can see the ongoing activity seen within the general vicinity of several supermassive black holes. (The most likely source of the x-ray emissions) The most prominent source of emission can be seen near NGC 3627's galactic center.
(In the composite, X-ray data from NASA's Chandra X-ray Observatory can be seen in blue. The infrared data (acquired by the Spitzer Space Telescope) can be seen in red. With optical data from the Hubble Space Telescope and the Very Large Telescope in yellow.)
See a larger version of the composite image here.