[TigerC10]

There is no difference. They are the same because of this code:

PHP Code:

$db = $vbulletin->db; 


It's just that not all of the PHP files have enough queries to warrant creating a $db object. Custom PHP files only have $vbulletin defined in them when you include global, so you'd have to create the $db object yourself (if you really want it).


The only reason for it, is to lighten the lookup load on the PHP engine. It's faster to lookup $db->query_write() than it is to lookup $vbulletin->db->db_query_write(). But it's not really noticibly faster unless you're running thousands upon thousands of queries at once.