What is the difference between PowerShell and cmd.exe command syntax?

What is the difference between PowerShell and cmd.exe command syntax?

I am running the following command in PowerShell:
PS C:\Users\adminaccount> winrm s winrm/config/service
@{AllowUnencrypted="true";
MaxConcurrentOperationsPerUser="4294967295"}
Error: Invalid use of command line. Type "winrm -?" for help.
Which gives me error, as you could see. But the same command in cmd.exe
works fine:
C:\Users\adminaccount>winrm s winrm/config/service @{AllowUnencrypted="true";
MaxConcurrentOperationsPerUser="4294967295"}
Service
...
So, what should I know about PowerShell syntax to get this working there?