Bin & Cue are used for Cd's and ISO can be both. Bin files tend to be smaller due to the fact there only used for Cd media.
Bin/cue was better for mixed mode cds since the cue has an index of where the data or audio starts and ends for each track. That allowed for a more precise layout of the tracks. For example, a game like Descent 2 that had both data and cd audio tracks. The cue file specified the start/end time of the data and the times for each track.