OK, without getting into the specifics of your data, let's just use a very simple use case that shows how you can compare the rows of tables in two different spreadsheets and then take action on them.
Say I have a sheet with vegetable names in it and a different one with fruit names in it and I want to be sure that they never overlap (i.e. there are no vegetables in my fruit list and no fruits in my vegetable list).
I'll store these sheets somewhere accessible, like OneDrive or SharePoint, then trigger my flow manually or on a schedule and start by listing out the files in that location to make sure they're there:
Now I will read all the rows from the tables I care about in those sheets:
And now I loop through all the rows in Sheet 1, then all the rows in Sheet 2 so I can compare them all side-by-side:
In that comparison, I render my local variables in Compose operations so I can debug if necessary later, and then check my condition: Do these match? If so, I will update the tables in both sheets to call out the matches I found.
Easy peasy.
So now, getting back to your use case, you want to compare two sheets to one list: the logic is the same. Get the sheet, get the list. Loop through the sheet rows, loop through the list rows, evaluate your condition and take action as needed. Then rinse and repeat for your second sheet. Easy peasy.
