The primary difference is that the NEX is a mirrorless camera. By getting rid of the mirror, the camera can be much smaller. Instead of an optical viewfinder like on an SLR, the NEX-7 has an electronic viewfinder. Another major difference is in the focusing. Most SLR's use phase detection AF, while the NEX relies on contrast detection AF. Generally speaking, phase detection is faster but less accurate, while contrast detection is slower but more accurate. Otherwise, the NEX-7 pretty much has just as many controls as a DSLR, they are just accessed differently. Mostly what the NEX system is currently lacking is a wide selection of native lenses, which may or may not be important to you.
So i want to know the difference, such as, what control differences does the nex-7 camera not have? (ISO, white balance, ect.) Which is better?