"What is the difference between a miracle, and something unexplainable?"
Generally, a miracle is defined as having some supernatural element, involving the intervention of a deity.
Amazing cures are frequently assessed as miracles by various religions.
In this case, the sudden cure of this nun's Parkinson's is supposedly due to prayers for John Paul II to intercede in the nun's behalf, after his death.
Since a miracle or two are required for the process of canonization to proceed, this case is of interest.
How does one know if it is supernatural or involves a deity?