The changes
The hands
Left hand then right, as the source writes them. A pianist's voicing routinely carries a colour the chord symbol does not spell — a flat ninth over a dominant, a ninth on top of a seventh chord — so the notes printed under each keyboard are what is actually played, rather than what the symbol alone would predict.
Cmaj7
chord 1
LH C2 G2RH E4 B4 D5
Db7
chord 2
LH Db3 Ab3RH F4 Cb5 Eb5
Dm7
chord 3
LH D3 A3RH F4 C5 E5
Ab7
chord 4
LH Ab2 Eb3RH C4 Gb4 Bb4