Complex sentence: But there are significant differences between AfD and RfD, chiefly that AfD debates are often focused on whether the topic is, whereas there is no standard or requirement for notability of redirects.
Split into simpler sentences: But there are significant differences between AfD and RfD. Chief among them is that AfD debates are usually focused on whether the topic is, whereas there is no standard or requirement for "notability" of redirects.