See: https://www.raspberrypi.org/products/model-a-plus/ The Model A+ is the low-cost variant of the Raspberry Pi. It replaced the original Model A in November 2014. Compared to the Model A it has: More GPIO. The GPIO header has grown to 40 pins, while retaining the same pinout for the first 26 pins as the Model A and B. Micro SD. The old friction-fit SD card socket has been replaced with a much nicer push-push micro SD version. Lower power consumption. By replacing linear regulators with switching ones we’ve reduced power consumption by between 0.5W and 1W. Better audio. The audio circuit incorporates a dedicated low-noise power supply. Smaller, neater form factor. We’ve aligned the USB connector with the board edge, moved composite video onto the 3.5mm jack, and added four squarely-placed mounting holes. Model A+ is approximately 2cm shorter than the Model A. We recommend the Model A+ for for embedded projects and projects which require very low power, and which do not require Ethernet or multiple USB ports.