Hello Dharwish,
The UD client is a very simple and well-tested Windows program. It just works. However, it lacks many interesting options. It is resolutely single-threaded, so it does not make full use of dual cores or multiple processors. It requires some work to run it as a service. Alternatively, it is fairly easy to run as a Scheduled Task. If you want to download a number of work units and return them in batches, you have to install UDMon and learn how to use it. The UD client allows you to run in screensaver-only mode if you allow the WCG screensaver to run on your machine. There is a simple way to throttle projects running under the UD client to a set percentage of the CPU.

BOINC is easy to install as a service and can run as many threads as you have processors or cores. It is easy to set up to run batches of work units (though this can introduce a number of complications). To throttle it, you have to use a third-party utility, such as ThreadMaster. BOINC does not compress files before transmitting them by default, the way UD does. BOINC, in fact, contains a number of bugs, though the number is rapidly declining. BOINC is already available for several different Operating Systems and comes with a good network management utility.

This is my idea of a simple compare-and-contrast.

Lawrence

Oh, don't be misled. UD has bugs, too - and a few conflicts with other software, particularly virus scanners.

The big problem with UD is it is proprietary, and United Devices seem unwilling to make any changes or fixes.