You have got different address cuz starting from the version 2.0 Electrum
derives keys and addresses from a hash of the UTF8 normalized seed phrase with no dependency on a fixed wordlist.
that isn't exactly the same as BIP39 scheme.
That's not accurate. Both address he gave are generate from the above BIP39 seed phrase at different derivation paths, as I showed in my last post.
Go to
https://iancoleman.io/bip39/Paste in the above seed phrase to the "BIP39 Mnemonic" field
Scroll down to "Derivation Path" and select "BIP32"
Under "Client" select "Custom derivation path"
Under "BIP32 Derivation Path" paste m/44'/0'/1'/1, scroll down, and the first address is 1Z1EM...
Under "BIP32 Derivation Path" paste m/44'/0'/1'/1'/0, scroll down, and the first address is 1NAxs...
Although Electrum by default doesn't use BIP39 seed phrases, when importing a seed phrase to Electrum you can click "Options" and select "BIP39 seed", as blue Snow must have done, otherwise he wouldn't have obtained the 1NAxs... address.