|Arduino Mega2560, Arduino UNO, Arduino Mini, Arduino Nano and Lilypad Arduino.|
These different form factor caters to different needs like size and height requirements, number of input/output pins, cost and shields compatibility. Please refer to the Arduino hardware page for the detail technical specifications. The software programming codes (called sketches) should be the same for most of the Arduino boards.
If you want to buy the first Arduino, please get either the Arduino UNO or Arduino Duemilanove (Duemilanove means year 2009 in Italy) available locally in your area. Trust me, since these are so low price, you will get a couple more Arduino, Arduino on a breadboard or Arduino clones for your future DIY projects needs. The Arduino brand can ONLY be used for official Arduino products and buying an official Arduino product is to show our support to the original creators for sharing with us such a powerful and easy to use microcontroller platform.
The Arduino UNO (or Duemilanove) have pins compatible with all the available shields (add-on modules on top of the UNO). The others like Mini, Nano, Mega and Lilypad board uses a different form factor and cannot be used with the Arduino shields. Some Arduino does not have USB chip on board and need either a USB-FTDI cable or FTDI breakout board for USB connection to the computer.
Since Arduino published all the schematics and diagrams, other companies also produces similar and differentiated duino products BUT they cannot use the Arduino name so they come up with similar names like Boarduino (Arduino on a breadboard), Freeduino, RBBB (Really Bare Bones Board), DFRuino, Seeeduino, Roboduino (for robotics) and Gator (rugged and fully protected). Some duino even have different colour PCB to suite your taste.
Some of these offering have fully assembled products or sold as a kit (unassembled) or just the printed circuit board (PCB) so that you can purchase common electronic components locally at a cheaper price or you enjoy soldering them yourself and save some money.
Due to popular demand, I am offering an Arduino UNO Starter Kit for beginners.