No worries, and maybe it will help to understand the different types of disc images.
First, be aware that each emulator handles the different disc image types in their own ways. For example, some emulators support ISO/MP3 but some don’t. Some require a CUE file and some will automatically search for the audio tracks even if there isn’t one. So just because it works in one emulator doesn’t mean that the disc image is actually good and proper.
Second, know the difference between redbook audio (ie, CD audio like in music CDs) and streamed or sequenced audio (ie, played from files in the data track).
Common disc image formats:
ISO - Everything is contained in a single file. In most cases, the CD audio isn’t accessible unless the emulator was specifically designed to search for it without a CUE track. ISO is an outdated format for Sega CD and PS1 games (among other systems) and should be avoided.
Single-BIN and CUE - All of the data and CD audio is stored in one BIN file. The CUE files lists the offsets of the CD audio within that file. It also has information about the disc “mode.”
Multi-BIN and CUE - This is the format used by Redump and is the recommended format to use with RetroArch. Track 1 is the data track. The rest (if any) are all CD audio. The CUE file lists all of the files and has information about the disc mode.
CHD - This is just a compressed disc image that stores the audio in a lossless way (FLAC, if I remember correctly). This is probably what most people use these days and most were built from Redump images.
As for the Spiderman example, what you’re not seeing in that BIN file is the CD audio data. The Redump image for that game is close to 600 MB, which is mostly because of the audio tracks. The data track is only around 60 MB or so. It’s very common for the data tracks to be so small compared to the CD audio for Sega CD games especially. A lot of later PS1 games started using streamed audio, so all of the audio is in the data track in those instances (Tekken 3 is a good example).