ESP32-PICO-D4 is an ESP32-based System-in-Package (SIP) from Espressif. The new ESP32-PICO-D4 SIP combines an ESP32 SoC, crystal oscillator, filter capacitors, RF matching links, and 4MB flash, into a single 7mm × 7mm QFN package.
ESP-12E is a miniature Wi-Fi module present in the market and is used for establishing a wireless network connection for microcontroller or processor. The core of ESP-12E is ESP8266EX, which is a high integration wireless SoC (System on Chip).