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

@property
def blocks_with_differing_constants(self):

    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
