Complex sentence: The difference between haematochezia and rectorrhagia is that in the latter, rectal bleeding is not associated with defaecation; instead, it is associated with expulsion of fresh bright red blood without stools.
Split into simpler sentences: The difference between haematochezia and rectorrhagia is that the latter rectal bleeding is not associated with defaecation. Instead, it is associated with expulsion of fresh bright red blood without stools.