[exim] sql query vs dsearch

Hi

Im using mysql for my virtual setup, and i recently found that for some
reason if i on purposely try to send to a supposed unrouteable address, then
the router "dnslookup_relay_to_domains", matches its conditions.

I narrowed it down to my local domains entry

So my question is, whats the difference between

domainlist local_domains = MAIN_LOCAL_DOMAINS :
dsearch;/etc/exim4/virtual_directory

vs

DOMAINLIST_FULL = SELECT DISTINCT domain FROM user
domainlist local_domains = MAIN_LOCAL_DOMAINS : DOMAINLIST_FULL

Kind Regards
Brent Clark