Hi aloeffle,
If you're doing scheduled backups of the switches from NetSight you can configure an alarm within NetSight to trigger on a configuration change. I believe there are some prebuilt alarms in NetSight, but you can also create one or limit it down to just the switch you're looking for by selecting that group. See attached screenshot.
As for comparing the two switch configurations, I believe you can only compare current and previous configurations of the same switch in NetSight.
Thanks,
Tyler