Noach Or Toldos

The opening words in parshas Noach and parshas Toldos are virtually the same.  Noach opens אֵ֚לֶּה תּֽוֹלְדֹ֣ת נֹ֔חַ and Toldos opens וְאֵ֛לֶּה תּֽוֹלְדֹ֥ת יִצְחָ֖ק בֶּן־אַבְרָהָ֑ם.  Yet the name of parshas Noach is Noach and parshas Toldos  is called Toldos.  Why is there a discrepancy in the name, or at least Noach should be called Toldos and only after that’s used up should Toldos be called Yitzchak?

As explained here, there was a major difference between the outlook of the Avos and the outlook of Noach.  Noach was satisfied by saving himself from the terrible generation but the Avos wanted to bring others under the banner.  Based upon this we understand that the name of the parsha isn’t just taking the first word of the parsha but it reflects the essence.  Noach is named Noach for the parsha is about Noach surviving the generation that completely was washed away.  Toldos is named Toldos is order to reflect the idea that the Avos wanted to give to others their message of God.  They wanted to make Toldos. (Based upon Likutay Sichos volume 25.)