Many services offer a CreateDraft and a Put operation. Both are used to add an item, but they operate differently.
The CreateDraft operation allows you to create a working copy of an item and continue to update it without immediately saving it to the system. For example, you can create a project and then set its name, project manager, and code as separate steps. This allows you to validate the data piece by piece, rather than all at once. Once the draft is completed, use the PublishDraft operation to save the item.
The Put operation allows you to add an item with a single call. All of the required data must be specified when you call the Put operation.