As you can see in the diff, considering only the first layer, it takes an input with 3 channels and output  a Tensor with 64 channels in the original one and 28 in yours.
This means that the weights of the first convolution are of size 64x3x3x3 in the original model and 28x3x3x3 in your case.
As you can see these two tensors have completely different number of elements.
So there is no way to copy one into the other, you would need to reduce the size of the original tensor to make it fit into your smaller one.
But then your first convolution will not do the same thing anymore and the output will be different. So the accuracy of the small model will be completely different from the accuracy of the original one.