Hydrogen exists in its native (I should say "terrestrial") form as a molecule comprised of two hydrogen atoms, and is denoted by the symbol H2 (in which, of course, the two is subscripted). Atomic hydrogen is a "free" hydrogen atom, or more accurately, a single proton. Hydrogen "wants" to be H2, and it is extremely difficult if not downright impossible to store any signifigant amount (now, you can store hydrogen in SWTs and that hydrogen will exist in its elemental form, but upon its release, it forms H2, and therefore I consider that to be different than a situation in which atomic hydrogen enters a container, and atomic hydrogen exits that same container).