快速答案
feriado 是法定假日的一天；férias 是一段假期。
可靠的方法是先判断这个词在句子里的功能，再翻译。
每个词的作用
feriado
public holiday
Use feriado for one officially recognized day when work or school may stop.
férias
vacation or school break
Use férias for a longer period away from work or classes.
如何选择
- feriado: Choose feriado if the sentence points to one officially recognized day when work or school may stop.
- férias: Choose férias if the sentence points to a longer period away from work or classes.
例句
A segunda-feira é feriado nacional.
Monday is a national holiday.
Vou viajar nas férias.
I am going to travel during my vacation.
常见误区
Férias is normally plural in Brazilian Portuguese, even when referring to one vacation period.
放到语境中练习
从你的真实生活中选一个句子，写两遍：一次用 feriado，一次用 férias。如果两个版本都可以，说明意思怎样变化。