Pre & Intra workout is most easily thought of as the energy system your body uses to get through strenuous activity. Certainly not a necessity but one of the most useful tools you can use to improve your focus, energy and recovery. When it comes to pre-workout decide between two categories.
Stimulant based - Usually caffeinated, hardcore focus based around the central nervous system a majority of the time. Non-stimulant based - Used for swelling of the muscle cell increases energy but more of a natural system.
Intra workout generally tailored to use whilst doing endurance events and long sessions. Often an overlooked supplement to get the most out of your session. Intra workout comes both stimulant & non-stimulant based.