Guns are utilized in a variety of spheres. They vary according to the type of substance they dispense.
Blow Guns - air guns & heat guns - are specifically designed to propel a stream of heated air onto a specific area. Such tools are commonly used in a multitude of spheres like engineering, chemistry, construction, plumbing, etc.
Spray Guns are utilized to propel liquids like paint, grease, lube, and similar substances. Dispensing guns distribute hard materials like tape, foam, and cord.
Cable Tie Guns are utilized to tighten cable connections. These devices do not propel anything but have the name simply due to appearance similarity.