What is the difference between #{expr} and ${expr} in jsf? Are there any cases when we should prefer ${expr}?

I've read some time ago about the difference in 'Core JSF' but now I can't find that place.

Nevertheless I don't remember that there was a word about cases when we should use ${expr} in jsf. So I'm just curious what is the difference (in a chestnut) and if there a case to use ${expr} in JSF application?