Pre-Trained Models Information required

Am trying to get hold of the params and symbols files for pre-trained models

METHOD 1:
model_name = “resnet18_v1”
net = gcv.model_zoo.get_model(model_name, pretrained=True)
export_block(model_name, net)

METHOD 2:
path=‘http://data.mxnet.io/models/imagenet/

[mx.test_utils.download(path+‘resnet/18-layers/resnet-18-0000.params’),
mx.test_utils.download(path+‘resnet/18-layers/resnet-18-symbol.json’),
mx.test_utils.download(path+‘synset.txt’)]

BOTH the methods export .params and symbols.json file.

I am curious to know what the difference between the two approaches.
Because the model files downloaded by METHOD B, works when exporting to ONNX
And the other ie(Method A) given an exception while exporting to ONNX

This tutorial would be helpful.
https://gluon-cv.mxnet.io/build/examples_deployment/export_network.html

net = gcv.model_zoo.get_model('resnet18_v1', pretrained=True)
export_block('resnet18_v1', net, preprocess=True, layout='HWC')