The Emblem aka Symbol aka Trademark - is the 'symbolic' component, an abstract depiction. The symbol is created to quickly establish a clear and unique representation for company, product or businesses.
The symbol, logotype and slogan can be used separately or not. The three elements can appear together or in some cases can be manipulated individually but not combined with other symbols, text, or lettering that can affect the generally your brand image.
Once a logo is designed, one of the most useful means for protecting it is through registration as a trademark, so that no unauthorized third parties can use it, or interfere with the owner's use of it. If you register the logo, the symbol "R" must always accompany the logo.