What is different about the neuromuscular junction compared to central synapses?
Neuromuscular junction is chemical communication between a nerve fibre and a muscle cell; central synapse is strictly neuron to neuron.
The neuromuscular junction is a junction (space) between the nerve fiber and muscle cell interact.
The central synapse is the junction between the axon tip and the dendrite of the receiving neuron.
That's the main difference, but in terms of structure and function, they are analogically similar.