Adverbs are words that add meaning to the verb and describe actions. They tell us when or how something is happening or where the action in a sentence takes place.
Quantifiers or intensifiers are adverbs of quantity or degree. They tell us how much, or to what extent, something is happening, eg me gusta mucho el cine (I like the cinema a lot) or los chicos hablan demasiado (the boys talk too much). They can also be used to add more detail to another adverb or an adjective, eg ella canta muy bien (she sings very well), los deberes son demasiado dif铆ciles (the homework is too difficult).