Intensifiers x Adverbs of Degree

Hey guys.

I have this question and would like someone to clarify this to me:

What's the difference between an intensifier and an adverb of degree? I know that Intensifiers are derived from Adverbs of Degree and belong to the same category, and I also saw that Intensifiers act are adverbs of degree, however, they can only modify Adjectives and Adverbs, whereas Adverbs of Degree can modify Adjectives, Adverbs and Verbs. Is that right? Is there any other explanation that you would like to give me? Thanks!