"Cardioid" is a type of mic. "Binaural" is a mic pattern.
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backwards...
Cardioid is a polar pattern. Binarual is a recording technique where a "head", either real or manufactured, complete with ears...is used. the mics are placed in the ear to employ the outer ear and physics combined. Mics are omni-directional (just like your ear). Playback is meant to be done via headphones only.