Time is up & Time is over!!!

[zoobinshid]

Hello everybody,
Would you please tell me the difference between these two sentences?
1)Time is up
2)Time is over

Thanks in advance,

[Mister Micawber]

.
To me, only the first sentence is natural; otherwise, they mean the same.
.

[panjandrum]

"Time is up" usually means that there is a time limit in doing something, say and hour, and when that time period has elapsed -- at the end of the hour -- "time is up" -- no more can be done.
Example:

"I was taking a test and in the middle of writing the proctor said time is up and I had to turn my paper upside down."

"The time is over" usually means that the opportunity to do something has passes, i.e. you missed your chance.
Example:

"The time is over to redeem that coupon."