Madara is a relic from a time when the Uchiha were thriving. Sharingan were everywhere so the Uchihas probably had their own vocabulary that they used when talking about the sharingan, classifications for describing what they looked like, and stuff like that. Sasuke didn't get to grow up in that world and only knows whatever it was Itachi had time to tell him.
So, Madara calling Sasuke's sharingan a choku tomoe may or may not be significant (as in, whether the type of pattern is heritable or an indication of what kind of power comes with it) and could just be a way of showing that Madara knows a lot about Mangekyo, and to illustrate the gap between Sasuke and Madara's knowledge. Sasuke might have the potential to grow beyond Madara, as Tobirama says, but Sasuke kind of has to learn a lot from scratch or just figure out how to defeat Madara with what he has.
