I can write what the Open Infrastructure Map is by using the words of its creator:
Open Infrastructure Map is a view of the world’s infrastructure mapped in the OpenStreetMap database. This data isn’t exposed on the default OSM map, so I built Open Infrastructure Map to visualise it.
But the best thing to do is tell you to head over to it and zoom in on areas you know. Being from Cape Breton, I did just that, and I was wonderfully surprised by how much detail was there. I think you will feel the same.