The Erica unit has power supply, an oscillator, an amplifier, a gate, a headphone amplifier wired to a jack, the full gamut of eurorack voltages, pots and switches wired and ready to go.
The product you're comparing it to is lovely and cheap and probably what I would buy, but the Erica device is much better for an electronics beginner-- it has a much lower barrier to get from tinkering to making the beeps and the boops.