Hi --- Contract period is the minimum length of time that you both agree to have the agreement in force, 12 months in your case.
Notice period is the minimum amount of notice required to end the service once the contract has expired naturally, after the above 12 months minimum contract period.
There had to be the 12 month initial "tie in" otherwise there would not be a point in having a 12 month contract that you could just end after 30 days. !!