Specifying negative answer: "This is not ... but ..."
a — but
To provide specifics on your negative answer, saying "No, it is not something. It is not something, but something else", say Нет, это неsomething. Э́то, неsomething, аsomething else."
Note that the order of statements is irrelevant, so the answer "It is not a farmer but an actress" is completely equal to "This is an actress, not a farmer".
— Нет, э́то не актри́са. Э́то фе́рмер, а не актри́са.
Is this an actress? — No, this is not an actress. This is a farmer, not an actress.
Give negative answers with specifics as shown in the examples. Click on the image to check yourself. You will see and hear both variants of correct answers.