:return: A list of block matches which appear to differ

def blocks_with_differing_constants(self):
        """
        :return: A list of block matches which appear to differ
        """
        differing_blocks = []
        diffs = dict()
        for (block_a, block_b) in self._block_matches:
            if self.blocks_probably_identical(block_a, block_b) and \
                    not self.blocks_probably_identical(block_a, block_b, check_constants=True):
                differing_blocks.append((block_a, block_b))
        for block_a, block_b in differing_blocks:
            ba = NormalizedBlock(block_a, self._function_a)
            bb = NormalizedBlock(block_b, self._function_b)
            diffs[(block_a, block_b)] = FunctionDiff._block_diff_constants(ba, bb)
        return diffs