Here's the breakdown:

* Physical Change: A change in the form or appearance of a substance, but not its chemical composition. This means the molecules themselves stay the same, even if their arrangement or state of matter changes. Examples include:

* Melting ice (water changes state from solid to liquid)

* Cutting paper (changes shape)

* Dissolving sugar in water (sugar particles disperse but remain as sugar molecules)

* Chemical Change: A change in the chemical composition of a substance. This means new substances are formed with different properties, as the original molecules break apart and rearrange to form new bonds. Examples include:

* Burning wood (wood reacts with oxygen to form ash, carbon dioxide, and other products)

* Rusting iron (iron reacts with oxygen to form iron oxide, or rust)

* Baking a cake (ingredients react chemically to form a new substance)

Key Takeaway: If chemical bonds break and new ones form, it's a chemical change. If the molecules remain the same, it's a physical change.