You are wrong – we recommend looking into the taxonomy. Apes and monkeys are not two different species, as you wrote. Apes (Hominoidea) are a branch of Old World monkeys.
Apes emerged within “monkeys” as sister of the Cercopithecidae in the Catarrhini, so cladistically they are monkeys as well. There has been resistance to directly designate apes (and thus humans) as monkeys, so “Old World monkey” may be taken to mean the Cercopithecoidea or the Catarrhini. That apes are monkeys was already realized by Georges-Louis Leclerc, Comte de Buffon in the 18th century.