Time is up or Time is over

[tulipflower]

Can I say 'Time's over' instead of Time's up at the end of a quiz? Are these two expressions different?

 

[emsr2d2]

Can I say 'Time's over' instead of 'Time's up' at the end of a quiz? Are these two expressions different?

You can but "Time's up" is more common (in BrE, at least).
Of course they're different - they use different words. A better question would have been "Do these expressions mean the same?"

 

[jutfrank]

I strongly dislike Time's over. For me, it's wrong. I mean, there may be cases where it works but if you mean to signal that a period allotted for a certain task has just come to an end, then say Time's up.