What is the difference between a spur gear and an involute gear?

A spur gear is a type of gear characterized by its straight teeth that are parallel to the gear axis, designed primarily for transmitting power between parallel shafts. In contrast, an involute gear refers to the specific tooth profile used in many gears, including spur gears, where the tooth shape is derived from an involute curve. This profile allows for smooth engagement and efficient power transmission, minimizing wear and noise. Essentially, while all involute gears can be spur gears, not all spur gears use the involute tooth profile.