I apologize, but I do not have specific information regarding the terms "R-CSS" and "R-SS" in the context of Morphy Richards OTGs (oven toaster grills). It is possible that these terms are specific to certain Morphy Richards models or product lines. Manufacturers may use various naming conventions and model designations to distinguish between different features or variations in their product lineup.
To obtain accurate and up-to-date information about the specific meanings of "R-CSS" and "R-SS" in the context of Morphy Richards OTGs, I would recommend reaching out to Morphy Richards directly or referring to their product documentation, website, or customer support for clarification on these terms. They will be able to provide you with the most accurate and detailed information about their products and model categories.