You're literally describing dynamic range. The volume is the same in the show and the advert, but the perception of loudness is completely different. You perceive the adverts as louder because of the reduced dynamic range, even though they're not actually louder at all. This reduction in dynamic range is done by pre-processing the audio [in the advert] with a compressor. It lifts the quieter sounds (reducing the dynamic range), which creates more of a 'wall of sound' but the overall decibel levels are the same.

https://www.uaudio.com/blogs/ua/audio-compression-basics