Explain why all linear angle pairs must be supplementary, but all supplementary angles do not have to be linear pairs?

Two angles are supplementary if their measures sum 180°.

Linear angle pairs are adjacent angles (they are together) and they form a straight angle, which is 180°. Therefore, they are supplementary.

But two angles may be separated and yet add 180°, then they are supplementary but are not linear angle pairs.

What the heck i didn’t know