Eles são duas coisas diferentes. A conta do sistema local deve conter o token para NT Authority\System
, de modo que não explique por que você está com problemas, mas certamente há diferenças entre as contas. Eles não são sinônimos um para o outro.
Esta advertência poderia explicar o que você está vendo:
A service that runs in the context of the LocalSystem account inherits the security context of the SCM. The user SID is created from the SECURITY_LOCAL_SYSTEM_RID value. The account is not associated with any logged-on user account. This has several implications:
•The registry key HKEY_CURRENT_USER is associated with the default user, not the current user. To access another user's profile, impersonate the user, then access HKEY_CURRENT_USER.
•The service can open the registry key HKEY_LOCAL_MACHINE\SECURITY.
• The service presents the computer's credentials to remote servers.
•If the service opens a command window and runs a batch file, the user could hit CTRL+C to terminate the batch file and gain access to a command window with LocalSystem permissions.