Black Dog

If you listen to the original song, you can notice that their is a chase going around between the drum beats and the guitar/bass progression. This is because of the time signatures of drums vs guitar/bass. The drums here are in 4/4 whereas the guitar and bass are in 5/4 and they meet together every 20 beats. Hence, that subtle difference in the drums and guitar/bass progression.

Here’s something which can help understand 5:4 Polyrhythm

Here’s an interesting read: Killer Changes of Time Signature, Syncopation, Pulse & Tempo in Led Zeppelin’s “Black Dog” (1971)