Hi Matt,
There is no startup-config on BOSS (ERS OS), only running-config.
The system use binary configuration file and can generate an ASCII format with "show running-config".
If you want to check all parameters, including default, you can with the "show running-config verbose"
But why do you want to compare the startup-config ? look to any loss of configuration ?
On some old release, there were some issue that can cause it, but it was corrected from while.
Regards,
Théo