The 'NES II', or 'New NES', is the redesigned Nintendo Entertainment System released in 1993. It is the North American equivalent of the Japanese A/V Famicom. The redesigns made it look more like the SNES and the system was sold for $50 to complement the more expensive Super Nintendo.
The case of the NES II is significantly different than the original NES. First, it is small, having about twice the footprint of a standard NES cartridge. This is a reasonable change, as the interior of an NES has a lot of empty space. This required that the front-loading design be retired for a SNES-style (and Famicom-style) top-loading design. The next time a major console system would be front-loading was the PlayStation 2. Unfortunately, there are some disadvantages to this design. First, there was no eject lever, so removing the cartridge required a significant, possibly alarming amount of force. Second, the different shape of the cartridge slot causes problems for some accessories that sat between the cartridge and the system, most notably the Game Genie. In the case of the Game Genie, an adapter was available to make it fit properly. The Power and Reset buttons were moved to the top of the system and the Power button made into an SNES-style switch.
The redesigned system came with redesigned controllers. These controllers resemble the Super Nintendo controllers in their layout and basic shape, with two circular areas holding the D-pad and A and B buttons, respectively, being joined by a square area with SNES-style tilted Start and Select buttons. The A and B buttons are also angled as on the SNES controller, and are slightly raised. The resulting controller is much easier to grip than the original square NES controllers, and are referred to as the 'dogbone' controllers.
Electronically, the system has three differences from the original NES. The more noticeable one is the lack of separate audio and video outputs, leaving only the RF output. This is rather ironic considering the Japanese counterpart, the A/V Famicom, lacks RF output and only has the separate A/V connectors. Another difference is that the NES II does not have the NES Lockout Chip in it, allowing it to play any* game made for the NES or Famicom. The third difference is the lack of an expansion port, as the NES-compatible version of the Famicom Disk System, which the NES's expansion port was intended for, was never made.
Since the NES II was released in the dying days of 8-bit gaming, it did not sell particularly well, making it considerably rarer than the original front-loading NES. By 1993, the 16-bit systems were receiving most new games. Nevertheless, the $50 list price allowed it to move more units than the original NES would have, with its list price only $10 less than the SNES.
*: A few unlicensed games were released whose method of circumvention required that the lockout chip be present, such as Firehawk by Codemasters.
Information from http://db.gamefaqs.com/console/nes/file/nintendo_entertainment_system.txt and http://www.atarihq.com/tsr/nes/newnes.html. More pictures can be found at http://www.vidgame.net/NINTENDO/NES2.html.
This writeup is copyright 2003 by me and is released under the Creative Commons Attribution-NoDerivs-NonCommercial licence. Details can be found at http://creativecommons.org/licenses/by-nd-nc/2.5/ .