It burns what you’re smoking at a lower temperature, so that less gunk goes into the air that you breathe in. That’s why the smoke from a vaporizer is a lot lighter and more “airy” than that from a pipe or a cigarette or joint.
When you smoke from a vaporizer, the leaves don’t really get burned the same way as with a cigarette or joint.
You can think of it kind of like the difference between grilling and steaming. Steaming is just kind of more delicate, it doesn’t produce a ton of smoke in your kitchen.
Using a vaporizer doesn’t make smoking completely safe, it just makes it less harsh.