Posture, attitude, pose denote a position assumed by the body, or the disposition of the parts of the body with relation to one another.
Posture applies to the relative arrangement of the different parts of the body. It may apply to a habitual or characteristic arrangement and then specifically means the way in which one holds oneself and refers to one’s physical carriage or bearing or it may apply to an arrangement determined with reference to the needs of the mood or the moment and then requires qualification or the assistance of the context to evoke a picture of how the parts of the body are disposed or to reveal the intention or end.
Attitude applies chiefly to a posture that is unconsciously expressive or is intentionally assumed, often as a result of a particular mood or state of mind.
Pose applies to an attitude or to a position of some part or parts of the body which is assumed for the sake of effect, or which, if unconscious, strikes the observer as effective or as affected.