How to simulation caffe2 by VTA?

Hi, everyone. I’m a newbie in TVM. I have some question about that how to simulation caffe2 by VTA.

Q1: What’s the difference between relay.frontend.from_caffe2(caffe2_model) and relay.frontend.from_onnx(caffe2.python.onnx.frontend.caffe2_net_to_onnx_model(caffe2_model))?

Q2: How to simulation caffe2 by VTA?

Please give me a hand. Thank you very much.