Small shells that are for consumer use are usually 1.75" diameter so they can be fired from a 2" ID mortar. They usually come with 6 or more reloads and a mortar. The image shows a 3" diameter, single shot shell that I obtained from a friend, and I do not know if it's legal. These are the same as professional class shells only smaller. They travel 100-200' up, then burst and release their payload of stars. Between firings from the same mortar, make sure there is no burning debris in the mortar as this could result in a reduced delay time.
Firecrackers are small (usually red) paper tubes containing a minute amount (~50mg) of flash powder. When used, they give a small report.
Ground spinners are paper tubes or discs, usually 1-2" long, that spin around on a flat surface. They are essentially tiny rocket motors with two nozzles on opposite ends and sides of the tube. Make sure that the spinner doesn't go into flammable materials as it spins.
Consumer starmines are very rare in the US, and I haven't actually ever seen one for sale. They are a mortar that has a bag with stars and black powder inside it. The black powder in the bag burns, sending the stars skyward.
Buzz bombs are essentially ground spinners with wings, so that they fly up instead of simply spinning on the ground. Sometimes at their apogee they release stars or explode as well.
Missile batteries are a block of tiny "missiles" that launch in sucsession. The missiles are like bottle rockets without the stick. Usually the "missiles" explode at their apogee.
Bottle Rockets are tiny rockets with a guidance stick. They are launched out of a bottle, usually. They may have a whistling boost stage, and most explode on apogee.
Skyrockets are rockets that are around the size of Estes B or C motors that are attached to a guidance stick. They're launched out of a tube. They travel higher and faster than bottle rockets, and most carry a payload of stars.
Missiles are like skyrockets in most respects, but they are designed to be launched from a flat space and have fins instead of a stick.
Fountains are like rocket engines, but instead of providing thrust, the exhaust plume is designed to be as entertaining as possible.
All multi-tube fountains are 2 or more regular fountains that are fused to fire in sucsession.
Roman candles are reminecent of a starmine in that they fire stars out of a mortar. The differance is that they fire single stars in delayed sucsession. It is advisible not to hold a roman candle in one's hand, however I have done it and I still have both hands.
Wheels, known by many other names, are designed to be stuck on a nail and the nail pressed into a tree or something. When the wheel is lit, 2 or more drivers, which are a cross between rocket engines and fountains, ignite and start the wheel spinning.
Sparklers are the only firework that is designed to be held in one's hand. Sparklers are a metal rod that's dipped in sparking composition. Make sure to hold the bare metal only, because the tip burns at upwards of 2000 degrees and can cause severe burns.
Strobes are little 1" balls of composition with a fuse sticking out of one side. They flash on and off with a blinding white light.
Snakes are weird little fireworks for daytime use that burn, leaving a long carbon ash that resembles a snake coming out of the ground.
Smoke "bombs" are paper balls with smoke composition inside them. They burn and release large amounts of colored smoke.
Novelty fireworks are almost no fun, do not buy them, even if they're all that is allowed in your state.