There are 4 main delivery systems for e-cigs. I'll list a few advantages/disadvantages of each, and a brief description.
Dripping
Dripping is basically having an atomizer attached to your battery, and you drip 2-3 drops of liquid onto the atomizer. Fire up the battery and draw. Rebuildable atomizers (RBA's) are designed so that they can be easily disassembled and re-wicked and coiled (requires some research to do properly).
Advantages: Truest flavor of the juice possible, as there is nothing to interfere with the flavor aside from the atomizer itself. A very good option for testing new flavors to see if you will like them without wasting much juice filling a carto, clearo or tank.
Disadvantages: You can't drip on the go. Each 2-3 drops might produce about 5-6 decent draws then you have to drip again, rinse and repeat. Best left till you have more experience with RBA (rebuildable atomizers) and/or you do it at home when you have nothing better to do such as watching a movie or whatever. EDIT: RBA's with a tank setup negate this problem, that is related to strictly dripping directly onto the atomizer.
Cartomizer
A metal tube, filled with a polyfill batting that absorbs the nicotine juice, wrapped around a wicking material. The wicking material brings the juice to the atomizer, which is heated by the battery to vaporize the juice.
Advantages: Small, portable, pretty inexpensive. Easy to carry multiple flavors of juice with you so you can swap flavors to suit you at any time, just unscrew the other carto and attach a different one. If you don't overfill, a cartomizer will not leak as all the juice is absorbed in the polyfill batting.
Disadvantages: You don't know how much juice you have left in a cartomizer for certain. Can easily burn the wicking material or polyfill batting if you draw too hard or there is not enough juice in the cartomizer. This results in a heavy 'burnt' taste, and often will ruin the carto. They have limited refilling capacity before the atomizer burns out (if you get that far) before they have to be disposed of. Good quality cartos can often have 30mL or perhaps a bit more juice run through them before dying out, but they have to be cleaned to get that far. Cleaning is relatively simple.
Clearomizer
This is a small tank design usually, which has a wicking system. The wick can be made of several materials (cotton, silica, and a few others). Some are rebuildable, others are not. Top coil clearomizers have the atomizer at the top, and wicks hang down toward the bottom. This produces a warmer vape, but can result in wicking problems with heavier (VG = vegetable glycerin) juices. Bottom coil clearos have a much shorter wick, and the atomizer is at the bottom. This results in a cooler vape (which some prefer) and often less wicking problems as the juice is always present near the bottom.
Advantages: Often the flavor is stronger in a clearo as there is no muting from polyfill to affect the flavor. Easy to fill and clean, store a decent amount of juice. Clearos (often) aren't that big so it's easy to carry a few flavors with you, but they are still larger than cartomizers and have the potential to leak. Most are clear-ish so you know how much juice you have left, which you don't with a cartomizer. Come in some variety (mostly colored) but not overly customizable.
Disadvantages: Can leak on some models easily, there can be wicking problems especially with the heavier VG juices leading to a burnt taste. Not all clearos are designed to be rebuildable, but most have an option to replace the head. Can crack with some strong acidic juices (cinnamon is a known culprit).
Tanks
A tank, or carto tank, is basically a cartomizer surrounded by an exterior storage device so you can hold more juice. The cartomizer is punched, to allow the juice in the tank portion to slowly feed into the cartomizer and replenish it as you use it up. The tank materials can be metal, glass, polycarbonate, pyrex..etc.
Advantages: Holds more juice than any other delivery system, though there are mini tanks that are smaller than some clearomizers...generally tanks are larger. They often have better sealing systems on them so they are less prone to leak than a clearomizer given proper usage. Gives a pretty true flavor with good liquid storage. Tanks are more suitable for flavors you really enjoy so you don't have to refill as often. Come in a variety of styles and designs, easy to customize.
Disadvantages: You have the advantages and disadvantages of a cartomizer. You can still burn up a cartomizer even inside a full tank if you didn't soak the cartomizer with juice previously (called priming), or if the holes punched in the cartomizer are not suitable for the juice you are using in the tank. Heavier juices require more holes to wick enough fluid into the cartomizer so that it doesn't burn up. Requires a small bit of knowledge to use a tank properly, but not any kind of difficult. Often requires a needle fill bottle or syringe to fill some styles of tanks. If it leaks, because tanks hold more juice it's that much more mess.
This is pretty general information, but hope it helps to give you an idea of things you can work with. Welcome to ECF bud.
