"Bonne journée" & "Bonne soirée"
I'm just curious, and not sure if it comes up at all in Duolingo or not, but.. why is it "Bonne journée" & "Bonne soirée" instead of "Bon jour" and "Bon soir"??
The difference between jour and journée, and between soir and soirée, is difficult to convey, but here's my attempt: jour refers strictly to a 24-hour period of time, whereas journée is more like the totality of what one's experiences and actions within that period of time.
It's like when a guy comes home from work and announces, "boy, what a day!" When he says "day", is he indicating that the inexorable passage of time - le jour - was particularly extraordinary? Probably not. More likely, he's referring to the combination of the commute, his idiotic boss, the tedium of the work, the quirky coworkers, and so on and so forth, that when put all together constitute "the day" - la journée.
Same situation with le soir and la soirée. Le soir is the period of time when the sun has set, is setting, is about to set, etc. The point is, it's just a time period. La soirée is what you did with that period of time - like going out to eat and then hitting the dance club. If those still exist.
we say both, the issue is not the meaning, the issue is just the 'usage' (how and when used]. If you question is when it is used, then the masculine Bonjour (attached) and Bonsoir, when you arrive to greet someone (like Hello) and the feminine when you leave and wish a good continuation (although bonsoir can be used when you leave to go to bed but thats for another day). It is attached though and not Bon Soir... and just usage so both can be used grammatically.