See this link for the comparison
Apart from that, VMware Workstation Player has a free for non-commercial use licence.
When you buy Workstation Pro, the Workstation Player still gets installed but given the features, chances are you will stick with the Workstation Pro UI.
I can only guess the Workstation Player is installed from the Workstation Pro bundle so that people can evaluate between the two if they haven't bought any licence yet.
Check if the following article helps:
Thank you, that is a tremendous help.@