The fastener decides the gun, and the guns here do not overlap. A nailer drives a nail, a stapler drives a staple, a blind riveter pulls a rivet from one side and a squeezer sets a solid rivet from both. A 2-in-1 gun takes nails and staples in the same body, which is the one place the categories meet. Reading the gun against the fastener rather than the other way round is what avoids buying a tool that cannot take what is already in the drawer.
Fastener size is the second figure and it is a range rather than a single number. The Draper nailer takes 10 to 50mm, and the PCL riveter is rated to 3/16 inch maximum. A gun will not drive a fastener above its range and will jam on one below it, so the range is read against the fastener already being used.
Blind riveters cover the joint that can only be reached from one side, which is most panel and enclosure work. The Chicago Pneumatic CP9886 and CP9887 sit here, with the CP4210 and CP4220 squeezers for solid rivet work where both faces are accessible and the joint has to be permanent. Squeezers need both faces reachable, which is the practical limit on where a solid rivet can be used at all.
Nut riveters set a threaded insert rather than a rivet, which turns thin sheet into something a bolt can be run into. Cordless 20V nail, staple and nut riveting guns are seated on the same leaf for work away from a hose. Fastener size and gun form are on every listing, and a photo of the fastener over WhatsApp on 07754288583 settles the match.