There are two main types of atomizers - Coil head atomizers (tanks) and DIY atomizers.
DIY atomizers has an ability to directly access rebuildable base, where are coils with cotton wool stored. Coils are attached to base with screws, which can be easily unscrewed in case you wanna replace an old coil with new one. That also gives an option to select wire type and affect desired coil resistance. However, the coil has to be placed correctly for proper function, therefore DIY atomizers are recommended for advanced users.
Coil head atomizers are also equipped with coil and cotton wool, instead of rebuildable base you can only find a chamber where coil heads are plugged or srewed. Coil with cotton wool is stored in encapsulated coil head, which makes them disposable and has to be replaced for new coil head when the taste begins to worsen. This type of atomizers are recommended for beginners, but also suitable for people prefering simplicity.
There are three different inhaling methods in both categories according to atomizer construction. DL (direct lung) allows deep inhalation similiar to inhaling water pipe. MTL (mouth to lung) provides restricted inhalation like tobacco cigarettes. RDL (restricted direct lung) makes a compromise between DL and MTL´s restriction.