The only significant difference is that it lets the instance overwrite the attribute (it doesn't have __set__ or __delete__). For example (using fractions.Fraction to demonstrate), the following:

    def __new__(cls, numerator=0, denominator=None, _normalize=True):
        # ...
        self._numerator = numerator
        self._denominator = denominator

    @property
    def numerator(a):
        return a._numerator

    @property
    def denominator(a):
        return a._denominator

would become:

    def __new__(cls, numerator=0, denominator=None, _normalize=True):
        # ...
        self.numerator = numerator
        self.denominator = denominator

    @attribute
    def numerator(a):
        pass

    @attribute
    def denominator(a):
        pass

This is more of an aesthetic enhancement rather than a functional one.