Pre workout supplements contain ingredients designed to increase the quality and performance of your workouts. These ingredients can help with;
Nitric Oxide supplements as the name suggests, contain ingredients purely to increase your nitric oxide production or "the pump" during training. Most nitric oxide supplements will contain no stimulants at all, acting as a good substitute for those wanting a pre-workout supplement with no caffeine.
Both can be taken separately or stacked together to really get the ultimate training experience!