I think there's a difference between OMNI and Omnicat. Omnicat is one of the projects launched on the OMNI network, while Omni itself is a layer-2 network based on the link you shared above. As far as I can tell, they're trying to be the layer-2 scaling solution for Ethereum, unless I misread their faqs. It doesn't help that there are other "Omni" projects out there, including probably one of the popular layer projects for Bitcoin, the Omni Layer.