As said in the glossary, tz accounts are called "implicit accounts" and KT1 accounts are called "originated accounts" or "smart contracts" (these two expressions are synonyms since Babylon).


If you want to move the keys, copy all the files inside ~/.tezos-client/ to the new machine. As you noticed, your secret key is encrypted, so even exposed by someone stealing your USB stick, they'd have to brute-force the encryption passphrase on your secret key in order to do any operations with it.

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