On the surface the new Nikon D5200 and the new Nikon D7100 may seem like the same DSLR camera, since they share the same excellent 24 megapixel APS-C sized sensor. This sensor (which is not the same 24 megapixel sensor found on the D3200) may be the best APS-C sized sensor currently on the market (although some will argue that the Fuji X-Trans 16 megapixel sensor and the Sigma Foveon sensor are better, but that is a matter of opinion).
So what are the real differences between the D5200 and the D7100?
With regards to image quality, there are no differences between these two cameras.They share the same sensor, built-in software and lenses. Both will produce excellent images in the hands of a capable photographer.
The D5200 has a flip-out screen while the D7100 does not. The D7100's screen is larger and has more resolution.
The D5200 has a 95% coverage pentamirror viewfinder while the D7100 has a 100% coverage pantaprism viewfinder. This may not seem like a big deal, but it is.
The D5200 is not weather sealed while while the D7100 is. This could be important depending on what conditions you may be photographing in.
The D5200 is smaller and lighter, while the D7100 has an extra memory card slot, slightly better auto-focus, and faster maximum shutter speed.
The D5200 is about 30% less expensive than the D7100, so you'll have to decide if the extra features of the D7100 are worth the extra cost. Both of these cameras are an excellent value, providing excellent image quality without breaking the bank.