Can Someone Explain Differences Between X-E1 and X100, Both Technical And IQ

Pardon my ignorance as I am a novice in photography and have used mobile devices and simple point-and-shoots for most part of my life. I am looking at both models and was wondering about the differences, or rather advantages that the X-E1 might have over the X100.

In what ways or areas the X-E1 is superior than the X100? I understand the X-E1 has the interchangeable lens option. How useful is this feature, and how do we select the appropriate or right lens for the X-E1 assuming that one only has to live with one single lens on the X-E1? How about image quality? It is often difficult to define image quality but does the X-E1 offer higher/better picture quality than the X100? In areas of sharpness, detail, colors etc. The specs look fairly similar to me - similar APS-C sensor, lens etc.

Any advice from knowledgable folks would be appreciated.

Thank you.