Date available = Date they could download it (i.e., your CAF was done)
Downloaded = well...please don't make me say it
There are reportedly some changes to the way that some programs see apps this year (the Web-based version is being trialled by some programs) so I can't comment for certain, but at least with the old system, once it was downloaded, that was all you knew. They may have dl'd it, shut off the computer and gone on vacation for 3 months for all you knew. There is (or at least wasn't as of last year) to know if anybody had ever bothered to read your app. The apps of those who get interviews and those who are screened out by filters will look the same to the applicant "Downloaded by program".
This is the reason I always harp on people to have their apps in as early as possible. You never know when, or how many times, a program will log on and download apps. Some do it every day, some will do it once or twice. If you're hat's not in the ring when that happens, you lose.