Vape pens are complete units: battery and cartridge together, ready to use out of the box.
The simplest way to vape without assembling anything. Starter kits and pod systems sit here alongside pen-style devices.
Vape pen, cartridge, or disposable?
A pen or starter kit suits anyone who wants one device to keep and refill. A separate battery plus cartridges gives you the widest choice of what goes in it. A disposable needs nothing at all and is used once. If you are buying your first, a kit is the middle ground: reusable, but nothing to work out.
See vape batteries if you already have cartridges, or distillate and vape carts for what to put in them. The Boost disposables carry 3g with nothing to charge. More hardware is in accessories.