There are several subspecies (at least 14) of the Brown-throated Parakeet which have varying colours particularly of the crown, face and underparts.
This is Eupsittula pertinax arubensis which occurs on Aruba and the northern coast of Venezuela.

1st, 2nd & 3rd photo: With a lot of patience, I somehow managed to get the bird on my finger! Arashi Beach area, Aruba, 27 March 2006
4th photo: Arikok National Park, Aruba, 21 March 2006