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"So many" is a phrase which is often translated as "tantos", and "that much" is an adverb which is often translated as "tanto". Learn more about the difference between "so many" and "that much" below.
so many()
A phrase is a group of words commonly used together (e.g., once upon a time).
a. tantos
Look at all these flavors! There are so many it's hard for me to just pick one.¡Mira todos estos sabores! Hay tantos que no puedo escoger solo uno.