From a practical standpoint, is there any real-world difference between Read/Write permissions and Create/Read/Update/Delete permissions? It would seem that if a user had the ability to 'create', he should always have the ability to 'update' or 'delete'? If this is correct, then read/write should always be sufficient, and there is no need to store separate Create/Read/Update/Delete permissions? Are there any real-world use cases in which a user should be given permissions to create but not update, or update but not delete, etc...?