Leela Zero's ELO graph assumes that 0 ELO is completely random play, as a simple reference point. On the other hand Alphago uses the more common ELO scale where

Leela Zero's ELO graph assumes that 0 ELO is completely random play, as a simple reference point. On the other hand Alphago uses the more common ELO scale where 0 is roughly equivalent to a beginner who knows the rules, so you can't directly compare the two.