They are very different, nvOC PXA Edition is a diferent breed of mining software, it compares, calculates, and changes your crytomining to the best and more profitable to mine. It need quite a setup , and is not really a system do constantly mine one coin, it has a builtin system for inteligent overclocking, and will reach, with enough time, a good overclocking. However configuring and getting the system to work properly is a bit complicated, but there is plenty of help available at the discord channels of the nvOC.
Cyclenerds Ethereum miner is a no nonsense approach to a mining OS, it does what is needed is a very efficient way. AND OPENSOURCE. Well worth donating
It has a menu for setting up the rig, and also a simple menu for setting up general overclock values(same value for all GPU), and supports custom overclock values, you can specify that GPU3 will run at a diferent power, and GPU4 at diferent memory clock ( this does involve editing a small settings.conf file where you would only add MY_WATT_3=110 ).
very simple and easy to make it run.
Keep in mind 1ºaction after 1boot is update in the menu. And of course change password....
You will have to get some tools to manage it, like SSH and SCP (in windows use putty and winscp).
This is a true opensource OS, very well built. Easy to change and update the miners.
I also use simplemining OS, because of AMD gpu rig, and there really it is hard to find a solution of a opensource solution.
Since your post is quite old, please do share an update on your finds.