Firstly, guns (sorry - am I writing correctly, I mean pistols?) are completely prohibited. You can buy any gun, but you can only store and use it at a shooting range, you cannot store it at home or in your car.
Secondly, there is a fairly clear distinction between shotguns and rifles. I mean weapons with rifled barrels (is it better to say a carbine or a rifle?).
A quick guide to assist you with how firearms terms are commonly used in the U.S. You're probably already familiar with a lot of the terminology below, so most of this may be redundant.
Firearm covers all categories of weapons.
Long gun is used as a general reference for all non-handgun weaponry, both rifles and shotguns.
Handgun is broken into
single shot,
revolver, and
semi-auto.
Single shot and
revolver are self-evident.
Semi-auto gets sticky at times due to a change in how term
pistol has been used over the decades. You will see the terms
pistol and
semi-auto used interchangeably even though the former technically denotes a category of firearm and the latter an action type. The historic term of "pistol" is synonymous with "handgun", meaning any weapon designed for one-hand use. In modern parlance it has evolved to denote a semi-auto handgun. Unfortunately, there is a lot of debate over the term's proper use so don't be surprise if it comes up and the debate becomes spirited. I will spare you the agony and simply leave it in broad terms. I will also intentionally not delve into the world of
single action and
double action, as that is an entire discussion of its own.
Rifles are usually referred to by their action type - lever, bolt, semi-automatic, etc. "Carbine" is typically used to denote a shorter version of an existing rifle. Example, a Winchester Model 1892 Carbine is a shorter-barreled version of the standard Winchester Model 1892 rifle. As with
pistol, the term often gets used as a general reference to any compact long gun rather than in it's more correct context.
Shotgun generally refers to any smoothbore long gun designed for shotshells, though some handguns will also accept shotgun shells. Shotguns generally come in three categories - single shot (or "breakover"), pump, and semi-auto.
Keep in mind these are all general-use scenarios. The English language's diversity is great for use as a tool to describe things, but the diversity also means it is easily morphed, warped, and bastardized in common use. How firearms terms are used in casual conversation varies almost endlessly, mostly based on historic use in a given region. That said, the above should work fine for you in the vast majority of situations.
Brad