Ah, right, OK. SQL Server doesn't capture any information like this by default, so you'd need to set up a computed column for SQL Compare or SQL Data Compare to have any access to that information. I'm assuming this question is actually about SQL Data Compare, given that you're talking about sorting by columns.
If you've got that DateModified column set up, then you can filter the data with a WHERE clause as detailed on this page:
http://www.red-gate.com/supportcenter/C ... Conditions
That ought to let you filter for changes applied within a specific timeframe. Does that help at all?