ESP32 Forum

Comparing it with Arduino as an example, Arduino itself isn't an MCU, the atmega328p chip on it is the actual MCU.
How about ESP32? is the little board called ESP32 or the chip? what about its CPU Xtensa LX6, isn't that technically the microcontroller?

On a classic Arduino, the name of the board as well as the environment you program it is Arduino, the chip is an ATMega and the core is whatever Atmel/Microchip calls their CPU core internally. It's a bit conflated there as you generally won't see AVRs without the AVR core and won't see non-AVRs with an AVR core. On Espressif chips, it's more complex as the Xtensa core isn't only used by us, and the chip itself lives on a little board called a 'module' to make the high-frequency RF stuff easier.. Here, the development environment is either Arduino or ESP-IDF (depending on which you use), the board is whatever the board you use is called (e.g. Espressif Devkit-C), the module is what specific module you have on your board (e.g. an Espressif Wroom32), the chip is an ESP32 (or more specifically, something like an ESP32-D0WD, where the last characters indicate e.g. on-board flash and the availability of two CPU cores), and the CPU core is a LX6.

I think it's easier to see as a table: By mentioning Arduino I mean atmega328p-based Arduino. Of course, there are any other MCU used, I'm just giving a context.