Review: Espressif ESP32-PICO-KIT Getting Started Guide
The ESP32 is the latest Espressif product. Like the ESP8266 it has Wi-Fi, but adds Bluetooth. Besides a flexible radio the ESP32 also has two 32-bit cores inside, making it extremely powerful, and it provides all the ports and interfaces that the ESP8266 is lacking. Oversimplifying things a bit, one might say that the ESP8266 is a Wi-Fi controller that provides some I/O, whereas the ESP32 is a full-fledged controller that also has Wi-Fi.