stabilityai/stable-diffusion-xl-base-1.0 · what is the format of stabilityai/stable-diffusion-xl-base-1.0 model?

I am confused by the format of the stabilityai/stable-diffusion-xl-base-1.0 model. Is it a pytorch model or is it an onnx model?

I tested ORTStableDiffusionXLPipeline.from_pretrained(model_id, export=True, provider="ROCMExecutionProvider",) vs ORTStableDiffusionXLPipeline.from_pretrained(model_id, export=False, provider="ROCMExecutionProvider",), it seems there is no difference for setting export to True vs False. Based on my understanding, if the model is already in onnx format, then this export argument will play no role here; but if it is in pytorch format, it should give me error message if I set export to False. Can anyone share any thoughts on this?

Thank you!