What's the Difference between Over the Air and WiFi for Marketplace?

[JohnMcD348]

OK, this is just for m own knowledge, no big deal but it got me wondering.

Sometimes, when I am downloading and installing a program from Marketplace, it requires that I either be tethered or on WiFi, but other times it works fine using only the OTA from my cellular carrier. I was just wondering what makes one program able to be downloaded/installed one way or the other. Is it something the developer requires? More apt for Games versus Applications? Is there any reason for one over the other?

What got me to thinking about it was today, I had a couple of notifications at different times from Marketplace. The first one I updated with no problem, the other, required I be logged into a WiFi connection to download and update.

Just wondering.