Notice of Intent to Deny (NOID) is a notice from the United States Citizenship and Immigration Services (USCIS) to inform the petitioner that his immigration petition is on the verge of getting denied by the evaluating officer.
Yes, NOID and RFE are different. Typically, RFE is a notice issued when the evaluating officer thinks insufficient evidence exists to approve the immigration petition.
Do not panic when you receive a NOID. It is not the end of your immigration petition.