Anything can be compared, and I wasn't the one who made the original comparison. I just pointed out that Garrett had won more games through this point in his career than Belichick had, which isn't a matter of opinion.
I don't think Jason Garrett is Bill Belichick. I tried, and apparently failed, to convey this by saying 'he's no Belichick.' But I guess that wasn't clear enough for everybody.
And I don't think Dak Prescott is Tom Brady either, for the record. Brady and Belichick aren't just generational greats. They're all-timers.