The difference is, A belt, is made from rubber with fibres woven in, They are strong, Quiet and cheap to make and replace they dont like being contaminated with oil, diesel or coolant, The chain is just that, Its like a big pushbike chain, It usually uses friction type tensioners, they are noisy, and not allways easy to swap they also need oil going to them, But the service interval is much longer. Oh yes, A chain is mechanically more complex too.
There are some horror stories about the V6 volkswagen engine chain drive as used in the galaxy, I will tell you later
If either breaks it causes just the same damage.