No, it isn't exactly the same. The SOAP Web Services API is much older than the REST API. The SOAP API used to have more functionality than the REST API, but the REST API is where all of the development effort is now.
With that said, if you can, you should use CMIS. CMIS has both a Web Services binding and an Atom Pub binding. If you cannot do what you need to do with CMIS, use the REST API. Use the Web Services API as a last resort.