[icegreentea]

We we're only talking about gameplay effecting purchases (so not skins and what not) I think it's used to draw the distinction between where you can purchase changes to gameplay that take effect in a mixed population of purchasers and non-purchasers (free to play), and where you can buy into access to segregated gameplay populations (free with mod marketplace).

For example, free to play in a FPS could be purchasing weapons that cannot be accessed in other ways. On the other hand, free + mod marketplace could say... imagine for some reason UT4 ships without a certain game mode... say CTF with Vehicles. Some enterprising fellow can now make a mod with CTF with Vehicles, and sell it on the marketplace. Or maybe a game mode where everyone has bow and arrow and a knife. The point is that there is now a 'different' game that you pay to get access to.

Fundamentally, it would be like say... if Half Life multiplayer was free on release, but someone still went and sold Counter Strike anyways.