Any nn.Module subclasses’ state_dict method returns a dictionary with the named parameters and buffers. Useful for storing and loading (via load_state_dict). The state dict does not contain any information about how these parameters are used, these are provided by the model.
VGG.features is the “feature extractor” (the convolutional part) of the VGG model, a submodule.
So they are really quite different things for different purposes.
Best regards
Thomas