The Raspberry Pi 2 Model B has a Quad-core 900MHz Processor, 1GB RAM, 4x USB Ports, 40x GPIO Pins, microSD connector and full 1080p HDMI video support. It’s almost as good as the Raspberry Pi 3 for about half the price. Now with Free 802.11n Wireless Adapter!
The Raspberry Pi 3 Model B+ (Released March, 2018) has a quad-core 64-bit 1.4GHz Processor, 1GB Ram and onboard Dual-band 802.11ac wireless LAN and Bluetooth 4.2 (including BLE).
This edition allows for PXE network and USB mass-storage booting and has a Gigabit Ethernet Network Interface.
The Raspberry Pi Zero WH is the smallest Raspberry Pi. It has onboard WiFi and Bluetooth. It has a micro SD card slot, a mini HDMI port, two micro USB ports (one for power, one for USB), and 512MB of RAM, and is powered by a single-core 1 GHz processor.