Both the Smile Brilliant Night Guard Packages and the Whitening packages come with everything you need to make your own impressions from the comfort of home. The difference is that the night guard system is designed to make only one impression (upper OR lower) where as the teeth whitening system will provide impression material for both upper AND lower.
Additionally, the trays you receive are quite different. Night guards are cut differently and are made from thicker material (to be more durable during grinding). Teeth whitening trays are thinner and designed to have a reservoir to hold the whitening gel in place.