I was reading Orberg's Lingua Latina per se Illustrata and I found the following sentences:
Marcus et Quīntus sunt dūo filiī. [...] In familia Rõmāna tres līberī sunt.
Now I deduce both words mean "children", but where would I use one or another? (I looked up at some dictionaries but didn't explained the difference).
Edit: This question has led to some kind of debate whether liberī is only applied to children that are born-free. See it.