Pyramidal cells activate other neurons, sometimes making connections with neurons that are quite far away. For this purpose they have long, insulated axons to carry the electrical impulses.
Interneurons (e.g., chandelier cells, double bouquet cells, spiny stellate cells, basket cells) have short dendrites and axons, and create network interactions between neighboring neurons. There are many different types of interneurons, but most are inhibitory, i.e. they suppress the activity of other neurons that are connected to them.