Why does my return journey seem shorter?

because your senses are taking the journey in on your first trip on the return trip your mind has already absorbed most of the possible information it will see and recognizes where it has been. the amount of tiome might be similar but your experience is different to you minds perception. or maybe you looking forward to getting home because you'll be on familiar ground. so it seems to shorten the time because you rellax knowing you be back to the familiar.