Onnx Vs Optimum

Hi, i would like to what is the difference between ONNX and Optimum. Basically what are the advantages i will be getting using optimim over onnx. Since if think onnxruntime focuses on efficient inferencet across multiple platforms and hardware. Similarly optimum seems to be leveraging the advantages that each hardware provides. So can i understand that optimum is basically a small speed up or small advanced version of onnx(apart from its ability of usage in other frameworks like coreml etc).