Batteries and supercapacitors store energy through different mechanisms, so neither should be selected from capacitance or voltage alone. Runtime, peak…
Compare a microcontroller with a single-board computer by real-time behavior, operating system, boot time, power, I/O and computing workload.
Compare Uno, Nano, Mega, Leonardo, Pro Mini and LilyPad by MCU, I/O count, memory, voltage, size and programming requirements.