As nouns the difference between dolphins and monkey
is that
dolphins is plural of lang=en while
monkey is any member of the clade Simiiformes not also of the clade Hominoidea containing humans and apes, from which they are usually, but not universally, distinguished by smaller size, a tail, and cheek pouches.
As a verb monkey is
to meddle; to mess with; to interfere; to fiddle.