The grammatical and structural difference between “Come here” and “Come to me” is actually very simple. In “Come here,” the word “come” is used as an
intransitive verb to mean “approach” or “move toward something,” with the noun “here” meaning “this place.” As we know, intransitive verbs don't need an object or an object of the preposition to receive its action; as such, it also doesn't need the preposition “to” as an intermediary device for that object. In contrast, in “Come
to me,” the word “come” is a
transitive verb that means “approach or be near something”; in this particular case, “me” is the object of the preposition “to,” which serves as the intermediary device for the action of the transitive verb “come.”
WHY SHOULD THERE BE “TO” IN “COME TO ME” AND NONE
IN “COME HERE” AND “COME HOME”?
In “Come
to me,” the word “to” isn’t an adverb; as already pointed out above, it’s a preposition that serves the intermediate function of receiving “me” as the object of the preposition
This distinction between “come” as an intransitive verb and as a transitive verb explains in the same way why
we don’t say “Come
to here,” “Come
to upstairs,” and “Come
to home,” but
we do say “Come
to church,” “Come
to me,” and “Come
to town.” “Come” is
intransitive in the first set of three statements, needing no object to receive its action; in contrast, “come” is
transitive in the second set of three statements, needing the nouns “church,” “me,” and “town” as objects of the preposition “to.”
We must also keep in mind that the preposition “to” is a function word that indicates “movement or an action or condition suggestive of movement toward a place, person, or thing reached.” When a speaker asks another person to “come” to “here,” or
the same place where that speaker is speaking, the direction of the desired movement is already obvious, so it has become idiomatic to drop or to no longer use “to” for such requests: “Come here,” “Come upstairs,” and “Come home.” This is actually a form of
ellipsis, the dropping of obvious grammatical elements as a way of streamlining and making statements more concise both in spoken and written form.
I trust that this has adequately clarified the usage of "come" as an intransitive verb and a transitive verb for you.