AME Hardware
AME Hardware
Arduino
The Arduino is a computer on a chip - CPU, memory for programs (ROM, flashable), memory for variables (RAM, volatile), memory for data (EPROM, non-volatile, runtime-programmable), counters, timers, I/O pins, and various interfaces (shared with the I/O pins; interrupts, serial, I2C, SPI). Different models offer different amounts of assets.
Cheap versions can be ordered from Chinese suppliers for 2.50€ a piece. I'm using them all the time, and they just work fine (didn't have a single dud in 20+ Arduinos).
ESP8266
The ESP8266 is IP and WLAN on a chip - SSL, TCP, UDP, WLAN, as a client or even as an access point (limited to 4 connections).
The ESP is its own microcomputer, just like the Arduino. And it can be programmed, just like an Arduino.
Why not just an ESP8266?
Good question! Less hardware, more memory, direct function calls instead of serial communications all sound good. But, the Arduino has more I/O pins. I found programming the ESP is slow, and the ESP is less forgiving when it is handled the wrong way, be it hardware or even software. I fried an ESP by just trying to blink on all I/O pins, to find out which number corresponds to which pin. After the ESP did not interact with the programmer any more.