PG is Propylene Glycol. VG is Vegetable Glycerine. PG generally tastes better with flavors added. VG has slightly less taste for the same amount of flavor added, but huge clouds of vapor.
Mix the two and you get the best of both worlds. My favorite mix is 70/30 pg/vg as sold by Don at
Backwoods Brew Try some 555 from them and you might find a daily vape.
Vaping will never be EXACTLY the same as tobacco cigarettes, but you will eventually prefer the Ecig for its taste and the vast number of flavors. Replicating the analog experience is best done with an ecig that feels like an analog (like the 510 and its equivalents). But, you will eventually want longer battery life and a larger cart that holds more juice.
The reason that ecigs don't taste like regular tobacco cigarettes is that there is no burning and no ash component in an ecig. When you smoke an analog, some of the microscopic particles of combustion actually make it through the filter and the tobacco into your lungs. These particles coat the inside of your lungs with tar and cause irritation. The lungs respond by coating over the particles and that can result in tissue growth that eventually becomes cancerous. Enough reason for the ecig being a better vehicle for your nicotine delivery? No? Well, PG is used in hospitals in breathing treatments to moisten the lungs, promote expulsion of mucous and to deliver medicines into the lungs. It's also being used in hospital HVAC equipment to introduce tiny droplets of pg into the air. The pg droplets collide with germs and sneezed droplets. When they collide, the heavier PG merges with the nasty stuff in the air and takes it to the floor, where it can be mopped up and discarded.
Vaping is, according to all sources, a better and hopefully safer way to get your nic.