Python-сообщество

 a = [{'say':'bla-bla', 'disk':'C', 'pl':'sh'}, {'say':'bla', 's': 'cr', 'something':'qwerty'}, {'say':'azsxd', 's': 'black'}, {'say':'rere', 'cast':'aaa', 'ss':'123'}, {'say':'44', '1':'1'}]
b = [{'say':'bla-bla', 'disk':'D'}, {'say':'bla', 's':'cr'}]

 class DiffObj(object):
    def __init__(self, list_one, list_two):
        self.list_one, self.list_two = list_one, list_two
    @property
    def sort_list_one(self):
        return [self.one for self.one in self.list_one if any(self.two.get('say') == self.one.get('say') for self.two in self.list_two)]

 result = DiffObj(a, b)
print(result.sort_list_one)

 a = [one for one in a if any(two.get('say') == one.get('say') for two in b)]