What are the differences in Raspberry Pi models?
The Raspberry Pi Foundation has just recently released a new model, the Raspberry Pi 2, which supersedes some of the previous boards, although the older boards will still be produced as long as there is a demand for them. It is generally backwards compatible with previous versions of the board, so any tutorials or projects you see which were built for a previous version of the board should still work.
There are a two Raspberry Pi models, the A and the B, named after the aforementioned BBC Micro, which was also released in a Model A and a Model B. The A comes with 256MB of RAM and one USB port. It is cheaper and uses less power than the B. The current model B comes with a second USB port, an ethernet port for connection to a network, and 512MB of RAM.
The Raspberry Pi A and B boards been upgraded to the A+ and B+ respectively. These upgrades make minor improvements, such as an increased number of USB ports and improved power consumption, particularly in the B+. The A+ and B+ have been reviewed on Opensource.com
If you have a Raspberry Pi and aren't sure which version you have, plug it in and from the terminal window, and run:
cat /proc/cpuinfo
The output will include a revision code. The numbers indicate further differences, but if it is 0002-0006, it is an older Model B with 256MB of RAM. If it is 0007-0009, it is a Model A. The newer Model Bs are listed as 000d-000f. The B+ is 0010, and the A+ is 0012. (Revision 0011 was used for the Raspberry Pi Compute Module.)