When I install the Alfresco, I can see two web applications. One is Alfresco Explore, another is Alfresco Share. Does anyone know what's the relationship between these two sites? I create a lot of Groups in Alfresco Explore, and I also want to use these groups in Alfresco Share, but I can only reuse the user, not the groups, does anyone know how to use them?
Alfresco Explorer and Share are sister interfaces. Both have the same mother (Alfresco repository) and some of the same abilities. Alfresco Explorer the "older sister" and is more capable. However Share is the "pretty little sister" and is growing up rapidly.
We are busily putting more group Support into share at the moment.
No they will never be combined into a single interface - they are two separate web applications, in fact Share can exist in a completely different server instance on a different machine than the main repository+explorer webapp.
Share revolves around a different metaphor, in that the content you want to expose for a Site is copied into it. We support content "linking" between sites and you can also use the Explorer client to Copy->Paste As Link or Copy->Paste as Link your existing content into a site documentlibrary folder to make existing content accessible. Sites are found in the new "Sites" folder under Company Home or you can use FTP into a documentlibrary folder etc. You can also setup Rules etc. using the Explorer client on folders under Sites.
There is not currently a way to browse the entire "repository" as it stands now in the Explorer - we want to move towards more context sensitive style of user content. We will be adding more ways to browse and find content in future versions of Share.