If you're buying a complete kit—battery and cartridge together from the same brand—you can ignore most of this. The manufacturer has already sorted compatibility for you. That's the easiest path for a gift. Also, if the recipient is a seasoned user who knows exactly what they want, you can just ask them. But if you're surprising someone who's new to this, the thread and fit are your responsibility.

Another group: people who only use disposable cartridges. If you're only ever buying pre-filled cartridges that screw on, you'll likely never hit a problem. But even then, a quick check of the thread type saves you from a dead stick.