Both can be changed by editing the registry. You can also save bits of the registry to a .reg file so you could make two reg files and run something to flip/flop between them.
If you are not a programmer, you might find that something like AutoHotKey would work for you. That lets you record and run macro's that you can easily play back via keyboard shortcuts and it has access to many of Windows' internal features such as direct registry editing. That would probably be more seamless than running a batch file to switch the registry files but either would work.
However. Unless you are really short of memory I very much doubt this would really help much. So here is the deal ...
Everything you put on your desktop is loaded into memory at startup. So to improve matters, simply get rid of all the rubbish, especially any large files and folders from the desktop and put them away tidily. If you want to use the desktop as a "menu", learn how to create shortcuts to the things that matter. shortcut .lnk files are small and so have little impact.
Then, if you are still short on memory, ditch the background image altogether. This will also help if you have a slow graphics card as less redrawing will take place - or rather less "stuff" has to be shifted around as you move windows around over the top of the image.