jour vs journée

I know that 'jour' = 'day' and 'journée' = 'day(time)', but can anyone clarify further on their usage? For example, if i want to say; "Votre sourire illumine ma jour/journée" ("your smile lights up my day") Which should i be using, or are they interchangeable? Thanks

Good question. I was taught that journée was also a "duration", while jour is more of a finite (countable) "time", so to speak. So, it should be [I think :)] : "Votre sourire illumine ma journée" [Your smile lights up my (whole) day.]

Thanks turusan, that makes sense. I thought journée sounded more 'right' though i wasn't really sure why!