You asked a great question. Earlier Intel® Desktop Adapters such as the Intel® PRO/1000 PT Desktop Adapter do not have software support for creating a team. In contrast, the Intel® PRO/1000 PT Server Adapter does support team creation.
When you look at the latest adapters, you will notice many differences. For example, server adapters often have multiple ports, add special support for virtual machines, and support security offloads. This is only a sampling of the differences. The individual product briefs give the details for each adapter. Talking in generalities is hard because the features vary between different server adapters.
If you have a desktop that requires a good performing gigabit adapter, then the Intel® Gigabit CT Desktop Adapter is a great choice. If you want the best adapter for a server handling multiple connections, then you have lots of choices depending on the traffic your server will be handling.
Intel® Ethernet adapters support standards based connections and a wide variety of operating systems used on both desktops and servers. You could use a desktop adapter in a server or a server adapter in a desktop if you wanted to.
The Product Selection Guide provides a handy comparison of many features, but the Guide does not tell the whole story. You can find detailed product and technology information at http://www.intel.com/go/ethernet.