'Posture', used as a noun, means the way a person sits, stands, the way they hold their head and shoulders. A posture may tell something about they way a person feels, but it may not be intentional. "His posture indicated that he was angry." "She had a relaxed posture, arms at her sides, with a serene expression on her face." 'Gesture' as a noun means some movement by a person to intentionally convey some message. Waving to a person is a gesture of friendship. Shrugging you shoulders is a gesture meaning that a person doesn't know something. "He gestured at Tom with his hand, indicated that Tom should come over." "She gestured with a wave of her hand that they should leave her alone." In short, a posture can be intentional or unintentional, a gesture is always intentional.

"Posture" is the way someone sits or stands. A "gesture" is a movement of the hands and arms and sometimes the body. Examples: She sat slumped in the chair, her posture showing how defeated she felt. The player made a rude gesture at the referee and was immediately sent off.