Two friends explore a product/concept together and discuss about it (with or without a moderator). Videorecording is used especially when no moderator is present.
Two participants (typically friends who know each other) explore the product together, freely discussing about it. Video is recorded and/or a moderator is present to guide the discussion. Sharing experience with a friend triggers typically more experiential comments than when discussing with a moderator.
May trigger more authentic experiential data than a normal face-to-face interview. The discussion might reveal interesting experiential aspects. Most suitable for investigating the initial responses to products.
Hard to control the direction of the discussion.