Arduino uno R3 Board is for science kits for kids,science projects,robot car on high school,primary school,secondary school.
1. Suture changes: AREF adds two I2C pins (SDA and SCL, only 4 and 5 analog copies, not an additional I2C interface). In addition, in addition to RESET also added two pins, one is IOREF, (Such as UNO 5 V, can be regarded as a copy of the power supply pin, does not provide level), the other is to use the placeholder Nail processing.
2. The RESET circuit is more stable. The RESET button position changes and moves closer to the USB interface near the gap.
3. ATmega16U2 instead of 8 u2, this does not mean that there is a 16k flash cd that can make your code run faster, the USB interface chip updates the service so that UNO can theoretically simulate USB HIDs such as MIDI / Joystick / keyboard