Because vaporizers don't burn, not only does vaping THC smell less, but the smell doesn't last as long, nor does vaping marijuana leave a smell on clothes as much as smoking. Smoking, because it is denser and heavier than steam, will keep the smell around even in a well-ventilated area. In general, vaporizers smell bad and you should take precautions to limit the amount of steam. The best option to reduce weed odor is to receive smaller blows.
In addition, it's a good idea to vape outdoors, as this makes it more difficult to determine where the smell is coming from. Getting a vaporizer designed to produce the least amount of odor is the first step to reducing cannabis odor. Although both vaping cannabis and smoking it produce a characteristic smell of cannabis, both the strength and quality of the smell are different in both cases. As an active vaper, I can tell you that regardless of the smell, the vapor will not stay in your room as long as cannabis smoke would.
Cannabis vapor is tar-free and has a much less potent odor because it lacks most of these toxic by-products. An on-demand convection vaporizer with a closed herb chamber will produce the lowest odor of all types of vaporizers. There is no way to create a vapor from cannabis without it smelling, so marijuana vaporizers are great, as they create very little odor that dissipates quickly. As the vaporizer starts to heat up to the predetermined temperature, you will absolutely smell a slight cannabis scent.
While there is a difference in odor between convection and conduction vaporizers, in my experience, this is the least significant factor in obtaining a vaporizer that produces the least amount of cannabis odor. Marijuana vaporizers don't burn weed, so you get more terpenes and cannabinoids when you use a marijuana vaporizer. A conduction vaporizer “fries” the herb and a convection vaporizer “bakes” the herb with hot air. Now, because an on-demand vaporizer generally has a stronger heater than a session vaporizer, the initial odor in the first minute or so remains strong and may even be stronger than the first minute of a session vaporizer.
A session-based driving vaporizer with a (partially) open herb chamber will produce the most odor of all types of vaporizers. So what is a marijuana vaporizer and how does it work? Knowing this, you can give you an idea of how much the marijuana vaporizer smells like.