As nouns the difference between tarsier and marmoset
is that
tarsier is an insectivorous primate of the
Tarsiidae family, having very large eyes and long feet, native mainly to several islands of Southeast Asia while
marmoset is a small monkey, now specifically a Central and South American monkey of the genera
Callithrix, genus: Cebuella, genus: Callibella, or genus: Mico, with claws instead of nails, and a rather primitive layout.