I'm not sure that you can learn anything from FCS games but if you can:
Ohio State beat YSU 35-7. In YSU's other two games they scored 52 and 48 while giving up 10 and 28.
Notre Dame beat TnSt 56-3. In TnSt's other two games they scored 24 and 27 while giving up 14 and 25.
It looks like Notre Dame had a better score (both offensively and defensively) but Ohio State played a better FCS team. That is all kinda hazy and a guess so I don't think you can make any significant distinction.
In their games against actual FBS opponents:

Ohio State looks the shakiest when you compare their performance against IU to Louisville's performance against IU. Louisville scored almost as much and gave up almost as little. Also, in both cases the Hoosiers never led. The difference is that Indiana scored both of their TD's against Lousiville in the third quarter so the entire fourth quarter of the IU/Lousiville game was a one-score game and on Indiana's last possession against the Cardinals they drove all the way to the Louisville one yard line. Louisville stopped them on a 4th and goal at the 1. In the IU/tOSU game the Buckeyes held a two-score lead throughout the 4th quarter and almost the entire second half so the game was barely in doubt past halftime.
Ohio State looks best when you compare their performance against WKY. The Hilltoppers have an otherwise prolific offense that has averaged 46.5 against opponents not named tOSU. The Buckeyes held them to 10. The Hilltoppers D hasn't been awful either. They gave up 24 to USF and tOSU nearly tripled that.
Notre Dame looks shakiest when you compare their performance against CMU. The Chippewas were held to less by MSU and scored gave up more against New Hampshire.
Notre Dame looks best when you compare their performance against Navy.
I really don't think there are enough data points here to make anything out of this.
Ohio State looks better than InSt, Louisville, USF, and Houston Christian. Notre Dame looks better than Wagner, Memphis, UCONN, VMI, MSU, and New Hampshire. Well that doesn't tell you anything you didn't already know.