The person who conducts the interview, such as a hiring manager or journalist.
The interviewer asked about the applicant's background.
The person being interviewed. Less common than 面接を受ける人 or 応募者 in everyday speech, but used in formal contexts.
The interviewee entered the room with a nervous expression.
応募者 means 'applicant' and is more common than 面接者 for the person being interviewed in a job context.
Compound of 面接 (interview) + 者 (person). The ambiguity between interviewer and interviewee arises because 者 simply indicates a person involved in the interview process.