Both are mining distributions for Ether. GenEthOs is free, EthOs is not. Both are based on Ubunut.
What's the difference between EthOS and GenEthOs?
GenEthOS support usb, hdd, ssd and wi-fi ) preinstalled proxy and genoil miner
GenEthOS Portable platform for Ethereum mining The way the OS was designed by a miner for miners in the first place for those who see all perspectives decentralized platform Ethereum
ethOS is a 64-bit linux distro that mines Ethereum out-of-the-box. ethOS is for large-scale deployment and its not free.
ethOS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version, as stated on their website.