VDP offers a few ways to define the retention policy, which are as follows:
Forever
For a certain number of days, weeks, months, or years
Till the specified date
Custom schedule
Custom schedule includes:
The difference between keeping backups for 60 days and doing daily retention for 60 days is that in the first case, backups older than 60 days will be deleted during the next backup job, while daily schedule will check and delete old backups daily.