Do these sentences mean the same thing?

[Grammarholic]

Do these sentences mean the same thing?

Last month the president signed the bill.

Last month the president had signed the bill.

Thanks.

[Mordant]

There is no difference in meaning, but the second implies that some related action followed. Often the past perfect refers to something in the past in relation to some later development.

The president had supported the measure three years ago, but sources reveal that they expect him to oppose its renewal.

The simple past would work there as well, though.

Different situation:

A: When did the president sign the bill, Larry?
B: *He had signed the bill last month.

A: When did you buy that hat?
B: *I had bought it last week.

The only correct answer is the simple past in those two.