they are not. the current consensus in computational neuroscience is that a neuron can be equivalent to a 2-layer or 3-layer ANN with point nonlinearities.
Edit: i am blocked from posting, so here are the refs:
Minsky and Papert showed that computing XOR requires a 3 layer artificial neural net: Input, Hidden Layer, Output - which has 2 layers of weighted connections.
This[0] research shows a single neuron can compute XOR, thus the artificial neuron has less computational power than a real one.
Edit: i am blocked from posting, so here are the refs:
https://www.ncbi.nlm.nih.gov/pubmed/20800473
https://www.ncbi.nlm.nih.gov/pubmed/25554708
https://sci-hub.tw/https://www.sciencedirect.com/science/art...