|This solves part of your problem:|
1. Insert a column between
Column A (Scheduled to Attend)
Column B (Actually Attended)
2. Type the following formula in cell B1:
=IF(ISERROR(MATCH(A1,$C$1:$C$150,0)),"No Match in Col C","")
3. Select cells B1:B150
4. Then "Edit", select "Fill" on the Edit menu, and then click “Down”.
This will compare who was scheduled (Column A) against who atteneded (Column C)and insert the comment "No Match in Col C" next to the name in Column A it could not find.
The columns do not have to be sorted, although it might be easier.
I Started at Row 1, change the formula if needed.
I used only 150 rows to check, again change if needed.
I inserted a column, because I find it makes it visually easier to determine the outcome.