KreateCD 1.1 features five different types of projects, all with different properties that you need in a certain case.
The ‘Classic’ in Classic Mode refers to KreateCD before version 1.0. In this mode you're able to add multiple tracks, which can be of all types. In theory it is possible to create a CD that works on a PC as well as a CD-player. TODO: REFER TO THE TRACKTYPES
The Audio only CD is made especially for creating audio CD's. While the interface looks the same as the classic mode, you'll only be able to add audio tracks to your project. Either the Audio or Audio Preemphasised track types.
A Data only CD (MC style), is a CD on which you can put one data track. You are able to select files and folders you want on the CD in a Midnight Commander way.