Differentiation between different components are made based on combindly Namespace,S/W Component, S/W component version, Product and Product version. When any component created in SLD is keeps reference of all these things. For example if you are creating one component then it has uniqueness with product, s/w component version, and with the help of others components as well. To know more about SLD in details you can refer help file of SLD which is containing details of all components in details and will give you an idea to diffentiate between them.
I hope this pdfs must help you to understand about SLD