Regrowth and Repair in Earthworm and Human

Human beings digit doesn’t regrow on getting amputated. But Earthworm regrows after getting amputated.
What can be difference which makes earthworm to regenerate but stops human digit to not regenerate?
The chatshaala whiteboard shows wound healing and scar formation. If a wound heals scar forms and we see the regeneration doesn’t take place, whereas in Earthworm we dont see wound getting healed and scar formation.

Can we know what is the reason scar formation takes place? And how can scar formation be stopped so that we can convert it into regenerating tissue?