What distinguishes a unipolar transistor from a bipolar transistor?

A unipolar transistor is characterized by its operation involving only one type of charge carrier, which can either be electrons or holes, but not both. This singular mode of operation allows unipolar transistors, such as field-effect transistors (FETs), to provide benefits like higher input impedance and simpler design compared to their bipolar counterparts.

In contrast, bipolar transistors utilize both types of charge carriers—electrons and holes—giving them different operational characteristics and applications. Since the question focuses on the core distinction between unipolar and bipolar transistors, the emphasis on the unipolar nature inherent to the unipolar transistor is essential for understanding its functional principle and its applications in electronics. This clarity on the charge carrier type directly influences the design and performance of circuits involving these transistors.