- The main difference is, of course, the license. Fosm content is licensed under the Creative Commons CC BY-SA license rather than OpenStreetMap's combination of Contributor Terms (CTs), Open Database License (ODbL), and Database Content License (DbCL). We think our license is much simpler and easier to understand. It relies on copyright which is the traditional mechanism for protecting maps and follows well known and understood legal principles.
- The fosm server platform is different and more technically advanced than OpenStreetMap. Rather than using a vast array of services spread across multiple servers, fosm runs on a single much smaller server. This is possible because we use a more sophisticated database and a very thin application layer.
- Way splits and merges are recorded more carefully in fosm than in OpenStreetMap. A special tag meta:predecessors is used to indicate if a version of a way has been derived from one or more other ways. This tag is generated automatically by fosm after any editing session.