up to five/until five

Question

a. The police had a list of the people who were in the building up to five o'clock.

b. The police had a list of the people who were in the building until five o'clock.

In which of the above sentences

1. It is possible that some of the people on the list left before five o'clock.

2. It is possible that some of the people on the list left after five o'clock.

?

Many thanks

Answer 1

These two have essentially the same meaning, although I would use the second sentence. Now, to your question:

1. No to both
2. Yes to both

What both sentences are saying is that the list is a list of people who did not leave the building before five o'clock.