There are two ways to obtain legal marijuana in Colorado, medically and recreationally. As of 2019, medical marijuana is available in thirty-three states and Washington DC. There are eleven states (and DC) where recreational marijuana is legal. In Colorado, we have both.
There is no difference in quality or general characteristics between medical and recreational products.
The only real difference in actuality is what your goal is, whether for medicine, such as pain relief, or for fun (or both). You could find similar strains and products in each store, though recreational stores tend to stock products that are higher in THC. Medical dispensaries, however, do not have the 100 milligram THC limit per package of edible. And medical and recreational weed is taxed differently. Each dispensary sale comes with a 2.9 percent state sales tax plus local sales tax (which varies). Recreational sales include state and local sales taxes along with a 10 percent retail marijuana tax.
If you go the medical route, you must have one of the qualifying medical conditions (Glaucoma, HIV, cancer, severe pain, PTSD, etc.) that Colorado accepts and visit a licensed physician. It may be that it fits nicely into your overall health plan. Once you get your certification, you join the Colorado Medical Marijuana registry, which is now all online. When visiting a dispensary, you need to have your certification with you at all times.
For both medical and recreational visits, you must have a valid government issued ID and be age 21 or over for admittance.