"The delegations from Beauxbatons and Durmstrang will be arriving in October and remaining with us for the greater part of this year. I know that you will all extend every courtesy to our foreign guests while they are with us, and will give your whole-hearted support to the Hogwarts champion when he or she is selected.
— Harry Potter
Does the meaning of greater part of a duration the same as best part of a duration? which both means the most part of a duration? Will the meaning change if the above quote is changed into "best part of this year"?