Contradiction in phase of reflected longitudinal waves

It isn't a contradiction. It is two different situations with different behavior. In the first, a sound wave reflects off a hard surface. A example is reflection from the closed end of an organ pipe. The second is reflection from the open end of an organ pipe.

A similar difference can be seen waves in springs. Here is a video from UCLA physics.

Its a bit weird to compare the phase of a wave and its reflection, since their directions are different. Both the sources you have put up are saying the same thing: Compressions are reflected as compressions, and rarefactions are reflected as rarefactions.

Now because their directions are different, the phase difference is continuously changing, so I dont really know what the books mean when they say there is no phase difference, or there is $180^ circ$ phase difference. The important thing to understand is the bold statement above.