An affidavit differs from a deposition in that an affidavit is:
An affidavit is a written statement, while a deposition is spoken testimony.
An affidavit is a sworn statement, while a deposition involves both parties.
A deposition is also a written statement, taken under oath, typically in a legal context.
Under CPLR 2301 and common notarial practice, an affidavit is a sworn written statement taken outside the presence of the opposing party, so it is ex parte in character and reduced to writing. By contrast, a deposition is testimony taken under oath in a proceeding or examination, typically with notice to the other side; the jurat on either instrument certifies the oath/affirmation was administered by an authorized officer.
Explanation
An affidavit is a written statement made under oath, and the source notes a jurat is attached to an “affidavit or deposition” to show it was properly made before an authorized officer. It is also ex parte, meaning “a hearing or examination in the presence of, or on papers filed by, one party and in the absence of the other.”