Recompute Ownership versus Copy Ownership to Next Year

How does the 'Recompute Ownership' job differ from the 'Copy Ownership to Next Year' job?

I understand that 'Copy Ownership to Next Year' copies OM data from the last period of one year into the first period of the following year. I also understand that a similar process happens automatically, where within a single year, the OM data is copied from one period into the next period.

If this is what 'Copy Ownership to Next Year' does, than what does 'Recompute Ownership' do?