I don't know enough about the different ways to partake of marijuana to articulate this with 100% accuracy, but a few years ago, while working part-time as a local crew guy for concerts that would come to town, we met a roadie that kept hitting a vape pen.
At the time, we had no idea what it was, and had no idea where the weed we kept smelling was coming from. We started talking about "someone's out here on stage smoking some good stuff," "must be a one-hitter somewhere," etc. and the roadie started laughing and was like "this is how I keep it on the down low. People smell it, but they never know who it is."
He then pulled his pen out, and proceeded to teach us of the mythical oil that you could burn via electricity. This was futuristic stuff back in 2009. He explained that he was from Cali, and that they were mostly using pens to smoke out there at the time, and the best weed came in thise tiny round plastic containers in the form of wax or oil. He told us that it would make its way "mainstream" in the midwest soon, and hooked up one of my buddies with some spare supplies that he had for free.
Roadies are so hit and miss, but that dude was cool. He could have ignored us, or told us to eff off and not worry about his weed, but instead, he educated us and then hooked us up with some Cali supplies in exchange for a good day of work from the local guys.