Seeed Studio XIAO SAMD21 carries the powerful CPU-ARM® Cortex®-M0+(SAMD21G18) running at up to 48Hz with 256KB Flash and 32KB SRAM on board and supports the USB Type-C interface which can supply power and download code. https://wiki.seeedstudio.com/Seeeduino-XIAO/

Seeed Studio XIAO SAMD21 carries the powerful CPU-ARM® Cortex®-M0+(SAMD21G18) running at up to 48Hz with 256KB Flash and 32KB SRAM on board and supports the USB Type-C interface which can supply power and download code. https://wiki.seeedstudio.com/Seeeduino-XIAO/

The Wio Terminal is a SAMD51-based microcontroller with Wireless Connectivity powered by Realtek RTL8720DN that’s compatible with Arduino and MicroPython. Currently, wireless connectivity is only supported by Arduino. It runs at 120MHz (Boost up to 200MHz), 4MB External Flash and 192KB RAM. It supports both Bluetooth and Wi-Fi providing backbone for IoT projects.

Adafruit ItsyBitsy M0 Express! Small, powerful, with a rockin' ATSAMD21 Cortex M0 #Adafruit #samd2x #part

XIAO SAMD21 powered by Microchip SAMD21G18 chip is an ultra-small, high-performance universal development board, the pioneering product of the XIAO series. It supports Arduino / Micropython / CircuitPython development, which is the perfect microcontroller for you to get started with electronics.

The Seeed Studio XIAO RP2040 is as small as the Seeed Studio XIAO SAMD21 but it's more powerful. On one hand, it carries the powerful Dual-core RP2040 processor that can flexible clock running up to 133 MHz which is a low-power microcontrollers. On the Seeed Studio XIAO RP2040 there is also 264KB of SRAM, and 2MB of on-board Flash memory which can provide more program to save and run. On the other hand, this little board has good performance in processing but needs less power. All in all, it is designed in a tiny size as small as a thumb(20x17.5mm) and can be used for wearable devices and small projects.