The Mega is a microcontroller board based on the ATmega2560.
Uno R3 is the ideal board for getting started with electronics!
The Leonardo ETH is a microcontroller board based on the ATmega32U4 and the W5500 TCP/IP embedded Ethernet controller.
MEGA+WiFi R3 ATmega2560+ESP8266, flash 32MB, USB-TTL CH340G, Micro-USB
The RobotDyn SAMD21 M0 represents a powerful, 32-bit extension of the Arduino UNO platform. The board is powered by Atmel’s SAMD21 MCU, featuring a 32-bit ARM Cortex® M0 core.