The difference between passive and active listening is that an active listener engages with the speaker while a passive listener simply receives the message without giving any external indications. Active listening has been shown to be more effective for retaining information, and also makes a speaker feel more comfortable.
Active listening can consist of both verbal and non-verbal cues. Non-verbal cues, such as nodding and eye contact, show that you are interested and engaged in what the speaker is saying. Verbal cues can vary from repeating or summarizing parts of what is being said to asking appropriate follow-up questions to engage the speaker.