Dreamcast: GDI vs Bin/Cue

I'm pretty new to Dreamcast emulation, but I wanted to get some files set up to put on a GDEMU. I thought GDI files were full rips of the discs, so my question is do I need the Bin and Cue files? I know for Playstation emulation, Bin and Cue are the main format. However, from how I'm understanding it, it seems like you would only need either Bin and Cue files or just GDI files.