Corona Project Manager (CPM) is for anyone who develops mobile apps using Ansca Mobile's Corona SDK or Corona Game Edition. It's a manager for all the projects and assets (source code files, graphics, audio files, etc.) that go into your app so you can quickly switch from one to another, swap out assets, and just generally have a smoother workflow.
Create as many projects as you like inside CPM, and then add as many assets as you like to each project. To launch a project with the Corona Simulator, just click the Launch button in the toolbar.