"Our youth study a lot!"
Translation:הנוער שלנו לומד הרבה!
The meaning is very similar but not quite the same. הנערים שלנו is either "our boys" or "or boys and girls", depending on context and situation. הנוער שלנו assumes something like a community, like a village/town/city or a nation or something in between, and refers to the teen age group. There are cases in which you could use either, but in other cases I wouldn't. For example, "the pupils of this high-school" or not הנוער שלנו.