DRHP stands for Draft Red Hearing Prospectus & RHP stands for Red Hearing Prospectus.
A DRHP is also known as the offer document. It is prepared by the merchant bankers appointed by the Company who wish to float IPO, as a preliminary registration document with SEBI.
A RHP is a preliminary registration document that is filed with SEBI in the case of book building issue which does not have details of either price or number of shares being offered or the amount of issue. RHP is Generally filled just before few days of IPO. It contains IPO Dates & Other Basic Schedule of IPO.