Are Cockatiels Cockatoos?

This a commonly asked question.

This is an exceptionaly beautiful yellow Cockatiel

This is a very rare Black Palm Cockatoo

In those pictures you saw, you noticed a similar feature with both parrots: the crests! The crest is the most obvious trait in Cockatiels and many cockatoos.

Also, Cockatiels and cockatoos share personality traits: like many of the cockatoos, Cockatiels enjoy being petted. Cockatiels also make noise a lot, but they are not nearly so loud.

But are Cockatiels really a small type of cockatoo?

According to wikipedia "The cockatiel is the only member of the gensus Nymphicus. It was previously considered a crested parrot or small cockatoo; however, more recent molecular studies have assigned it to its own unique Cockatoo subfamily Nymphicinae.

Thus Cockatiels are cockatoos, but they are in their own gensus.