???? What it means is that his wins are more spread out on all slams whereas 66.7% of Nadal’s titles are at 1 slam. It means Nadal is more specialized.You do realise you have just made Djokovic half the player of Nadal don't you. Djokovic is a hard court specialist by your logic yet cannot even have a better win ratio on his best surface than Nadal despite double the opportunity.
Perhaps you care to revise your post.
Djoko: AO = 46.7%, W = 26.6%, USO = 20%, RG = 6.7%
Nadal: RG = 66.7%, USO = 16.7%, W = 11.1%, AO = 5.5%
So, Nadal has a much higher % in his best slam than Djoko and a lower % in the other 3.