Firearms and air guns: Can you tell the difference?

(CNN)Tyre King had a BB gun when an Ohio police officer shot and killed the 13-year-old in Columbus, police say.

Two years earlier, a police officer fatally shot 12-year-old Tamir Rice in Cleveland while he had an airsoft gun.
In both instances, police say, the boys were shot because they were drawing guns that the shooting officers mistook for standard firearms.
    "It looks practically identical" to the type of handgun that police carry, Columbus police Chief Kim Jacobs told reporters about the BB gun that King allegedly had.
    How closely do BB guns, pellet guns and airsoft guns resemble a traditional firearm? And how do they differ in function? Take a look for yourself.
    Above, you'll see a breakdown of the differences, with guidance from Jay Wallace, owner of gun and hunting equipment store Adventure Outdoors in Smyrna, Georgia. The BB gun shown here -- an Umarex 40xp -- is the type of BB gun police say King carried.
    All four types can be pistols or long guns, but here we show only pictures of pistols for ease of comparison.