Following on from a previous article relating to checking the farm patch level, I have quickly documented how to check Project Professional 2010 patch level below. The previous article can be found here: https://pwmather.wordpress.com/2011/07/08/how-to-check-the-sharepoint-2010-and-project-server-2010-service-pack-patch-level-ps2010-projectserver-sharepoint-sp2010/
To check the patch level for Project Professional 2010, launch Project Professional 2010. Click File > Help > Additional Version and Copyright Information
A dialogue box will appear like the one shown below:
The version number can be seen on the first line.
It is best practice that the patch level of Project Professional 2010 matches the the patch level of Project Server 2010.