The commands you've listed here are outlined in Hub KB 10869:
https://community.extremenetworks.com/extreme/topics/capturing_securestack_error_messages_in_the_log...
They are intended to affect what is written to the logging buffer (from master unit only, saved until system reset) and the syslog server.
This logged data has some overlap with what is written to the current.log (aggregated from all stack units, saved to non-volatile memory), but it is in general not a record of the same events.
I don't know of any detailed explanation of the differences, however I believe that the rationale is that keeping long-term track of the additional debug messaging has the potential to quickly fill the current.log's available 256,000-byte storage and place it into auto-wrap/overwrite mode - for little resulting diagnostic value.