What is the fundamental difference in light behavior that makes planets typically not twinkle?

Answer

Planets present a small disk of light, averaging out atmospheric disturbances

Planets appear steadier because, even though they look like points without a telescope, their apparent size is significantly larger than a distant star, causing atmospheric disturbances to average out across the light disk.

What is the fundamental difference in light behavior that makes planets typically not twinkle?
astronomystarMooncelestialbright object