Between the two neurons in reflex arc there is a gap called synapse.
If the synapse is filled with neurotransmitter like acetylcholine then it is called chemical synapse otherwise it is called electrical synapse.
Impulse passes from one neuron to other neuron through synapse the neurotransmitter like acetylcholine present in the synapse helps in the transmission of impulse.
The two neurons in the electrical synapse are very close to each other than chemical synapse hence the transmission of impulse in electrical synapse is faster than chemical synapse.
Thus the electrical transmission of impulse is faster than chemical transmission of impulse.