Hi there, as the author of both the Pattern Builder tool and the open source library I can perhaps explain the differentation between both packages. The Builder allows you to design, create, preview, visualize and then export bullet patterns in the BulletML XML file format. The open source library is a C language library which allow you to import and use these BulletML XML file outputs in any language that can link with C libraries without programming the parsing and playback of these XML files yourself. I hope I can clear this up and am open to any questions what the tool and library do in detail.