The difference in one paragraph
A one-way NDA protects one side's information: the Disclosing Party shares, the Receiving Party is bound. A mutual NDA binds both sides symmetrically. The common mistake is signing a one-way NDA as the receiver while also revealing your own confidential material — your information then has no protection at all. An NDA’s direction follows who actually reveals something worth protecting, which is not always the side that proposed the document.