WARNING: This product contains nicotine. Nicotine is an addictive chemical.
Disposable is used to describe products that are fully functional, but are not rechargeable. Therefore, once the battery is depleted they can no longer be used and are simply thrown away. They are great for introducing someone to ecigs or as a trial just to see if electronic cigarettes may be a viable option for the user before committing to a more expensive device. Many users also prefer them for traveling as they are self contained and don't require the user to carry additional equipment such as chargers or replacement heads.
This category contains your standard electronic cigarette / personal vaporizer starter kits. Basic and simple, they are easy to operate and generally don't have any bells and whistles. They provide a consistent experience by always putting out the same voltage and are usually cheaper in comparison to the more advance batteries available.
This category contains all starter kits that have batteries with variable voltage capabilities. By adjusting the voltage of the battery the user can customize and fine tune their vaping experience. With all other factors being equal, turning the voltage up will cause the heating element (coil) inside the tank or atomizer to burn hotter, which usually provides a fuller, warmer vape. Experienced users have also noticed that some flavors may change slightly or just taste a little better at different temperatures, so being able to change the voltage allows them to dial in just the right flavor and vapor production. However, since the coil is wrapped around a wick on the inside of the tank or atomizer, if the voltage is set too high (or if there is not enough liquid or airflow to keep the coil cool) then it can burn the wick, which results in a very bad taste and possibly permanent damage to the wick causing the taste to linger. If this occurs it is best to turn the voltage down immediately and wait a minute or two for the coil to cool before taking another puff. Another downside to variable voltage is that when changing to a different tank or atomizer, or even just replacing the coil in the same tank, the user will likely have to dial the voltage in again optimize taste and vapor production. This is especially true if the new atomizer or tank has a different resistance since the resistance also effects the temperature at which the coil heats up.
Adjusting the wattage can provide a similar fine tuning of the vaping experience as adjusting the voltage, but wattage can be a little more difficult to understand than voltage. Once you know how it works it seems simple and is preferred by many users due to the consistent experience it provides. Essentially, wattage is a function of the voltage output of the battery and the resistance of the coil in the tank or atomizer. However the voltage and resistance relate to wattage in different ways. Voltage and wattage have a positive correlation, so an increase in voltage from the battery results in an increase in the overall wattage. On the flip side, resistance and wattage have an inverse relationship, so a decrease in resistance of the coil results in an increase in the overall watage. What this means for the user is that with a variable wattage battery they can set their wattage to a level that provides the perfect vaping experience and the battery will automatically adjust the voltage output based on the resistance of the coil so that this experience remains the same. This remains true even if the user changes the tank or atomizer to a completely different product with a different resistance. The battery will simply turn the voltage up or down so that the wattage is the same and therefore the coil burns at the same temperature and provides the same taste and vapor production. The user can still turn the wattage up or down if they prefer, but most users tend to fine tune their device for optimal output and end up adjusting it much less often than with a variable voltage battery.
"Mod" is a term used to describe the more advanced electronic cigarette devices also known as Advanced Personal Vaporizers (APV). They are often much larger in terms of size and capacity and usually have many more features and benefits that allow the user to truly customize their vaping experience. While they may be a little too advanced for someone that is new to vaping, they are definitely preferred by those that have turned vaping into more of a hobby or simply want the best experience available.