Import PFXCertificate

Is there any difference how pfx certificate is imported? When I import it using mmc certificates snap-in a file is created “C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys\177aa5d81f1b7053089685c5503be65c_fd233b81-f172-4881-9db1-a45ed9d45116” and when I import the same pfx certificate using Import-PfxCertificate cmdlet that file is not created. What is this file for?

One more thing, after import using cmdlet I checked the PrivateKey property and it turns to be empty

$cert = Get-Item -Path Cert:\LocalMachine\TrustedPublisher\A819AFC278405F9E82A620384784A2223C4EBFF9