There is a huge world of Over The Counter (OTC) or also called Non-Prescription Medications. In fact, this world continues to grow as more and more prescription medications move into the Schedule 3 or non-prescription medication status. In fact, to help you keep this straight, here are the schedules as they apply in Alberta, Canada (each province will be slightly different) understanding that every part of the world will have their own regulations that apply to all medications.
Schedule 1: prescription only medications. Require a prescription from a designated healthcare provider. (eg. oral antibiotics, blood pressure medications, antidepressants, etc.)
Schedule 2: non-prescription medications. These do not require a prescription but access to these are supervised by the pharmacist for a variety of reasons. (eg. Iron Supplements containing 60mg to 100mg of iron per tablet, products containing 8mg of codeine in combination with two other ingredients, dimenhydrinate (Gravol) packages of more than 30 tablets, pseudoephedrine products as the single ingredient, etc.)
Schedule 3: non-prescription medications that are available for self selection. (eg. Benylin, Robutssin, Senokot, Tylenol Extra Strength tabs/caplets, Ibuprofen 200mg, 300mg, 400mg, etc.)
Schedule 4: these are unscheduled and can be purchased in a wide variety of locations many of them non pharmacy locations. (eg. Very small convenience package sizes of Tylenol, Ibuprofen, etc.)