There are currently many phenotypes of cannabis, shortened colloquially to “Type”. These are not to be confused with strains (Blue Dream, etc) or species (Sativa, Indica, Ruderalis). These types are mainly marketing terms to refer to the selective breeding of plants but beyond such specificity as strain.
The types are as follows:
Type 1 - Sometimes romanticized as Type I, this is the weed you are familiar with. Bred for high THCa, this is the most common form of weed in the US market.
Type 2 - Also known as Type II, old weed, and 1:1 weed (albeit coming in many ratios), this weed is higher in CBD and resembles a more natural plant. It is common to see the two in a one-to-one ratio of THC to CDB. Sometimes this can be found in other ratios, but the CBD is still substantial.
Type 3 - Type III weed is sometimes called Hemp Weed. This is because it is mainly CBD, and often has little to no THC.
Type 4 - Type IV weed (and beyond) is done with some genetic work. Basically, they remove the THCa and CBDa synthase, and the result is a weed that grows CBG as its primary cannabinoid.