Vista - Windows Defender Scheduled Scan

Normally, Windows Defender reports to have scanned approx. 550,000 objects when completing a full system scan. Then suddenly, I see full system scans being completed of over 1,200,000 objects or just more than double. What could account for such a large increase in scan size on my system practically overnight?

Defender defaults to quick scan- full scanning is the entire computer. settings can be changed in tools>options

I think you might have misinterpreted my question. I understand the difference between quick and full scans and their prospective areas they scan. What I was asking was when I set Defender to do a full scan, the number of objects indentified and scanned was approx. 550,000. Lately, though, when I set Defender to do a full scan, it identified and scanned approx. 1,200,000. And, I was curious as to where the additional 700,000 objects came from and what they could be.

evidently the size of your drive(s) has increased.