Function diff 

pub fn diff(
    from: &ProjectState,
    to: &ProjectState,
) -> Result<Vec<Operation>, MigrationError>

Operations that turn from into to, in a deterministic order:

1. Delete constraints, indexes, fields
2. Delete models (reverse FK dependency order)
3. Rename fields
4. Create models (topological by FK dependencies; cyclic FKs are deferred as Operation::AddField)
5. Add / alter fields
6. Create indexes and constraints