>>41136502Dynamax - Can be used by every Pokemon. The Pokemon just gets bigger and its voice is loud and deep. All of its status moves become Max Guard. All of its type damage dealing moves become the generic Max Move of that type.
Gigantamax - Can only be used by some species of Pokemon, and even then only a select few members of those species can Gigantamax. Can only be obtained through gifts and Max Raid Battles, but are very rare in MRBs. A Pokemon's physical appearance actually changes. Two Pokemon, Flapple and Appletun, share the same Gigantamax appearance, however. Each Gigantamax has the generic Max Guard for all status moves, and generic Max Moves for most types. But one move type (one of their two Pokemon types) for each Gigantamax is changed to a species-exclusive G-Max Move, which offers more specific effects than the Max Moves. Max Moves usually change a stat of a Pokemon, or set up weather or terrain, but a G-Max Move can set up rocks, screens, spikes. heal Pokemon, inflict Yawn status, etc.
