What is the difference between seltzer, sparkling water, club soda and tonic?

Seltzer and Sparkling Water is plain water with added carbonation to make the water bubbly. This can be made easily with a SodaStream Sparkling Water Maker. Tonic can also be easily made with a SodaStream Sparkling Water Maker by carbonating plain tap water, and then adding Tonic Soda Mix to the Sparkling Water. Club Soda is very similar to seltzer or sparkling water, but additional ingredients are added to create a unique flavor.