ADF stands for ‘Amiga Disk File’ and is a 880 KiB image of an Amiga floppy disk. In this image format only the real bytes on the disk are preserved, so any physical copy protection on the floppy can’t be saved in this format. This is why mostly only cracked games are stored in this format (or games that have no physical copy protection).
IPF stands for ‘Interchangeable Preservation Format’ and is a ‘low-level, representing the information as it would have been read by a drive head’ format. This format stores all the information on the disk and is able to reproduce physical copy protections. Mainly original (and physically copy-protected) floppy disks are stored in this format.
The online game database (and FS-UAE Launcher) supports floppy-based games in these file formats, as well as the DMS file format (less commonly used).