I think Fabregas had a higher ceiling, but also a lower floor than Odegaard.
Their stats across all seasons in the Premier League are comparable with Fabregas scoring/assisting in .48 games and Odegaard at .44 games. That's a marginal difference, but where Fabregas takes the output consideration is in his 09/10 season with 30 goal contributions in 27 games. Odegaard has peaked at 22 in 37, a noticeably less efficient volume.
That said, outside of a few cowardly performances at Liverpool, I think on his worst day Odegaard is noticeably better than Fabregas at his lows. Odegaard has a far bigger impact on our defensive pressing and shape.
I'm not sure how to gauge our current team in which Odegaard really only has Saka (going forward) vs Fabregas playing in teams with Nasri, RVP, Arshavin, and Walcott....though rarely all together. It seems that Fabregas had more offensive players to enhance his output, where as Odegaard has a far better backline supporting him.