Magento config.xml system.xml adminhtml.xml -

can pls shed light on below topic ?

what clear difference between magento's etc/ config.xml, system.xml , adminhtml.xml ?

what code differentiate 3 of above xml files ?

it core magento knowledge.

the config.xml files contain global configuration information magento, available magento "areas". in beginning, there no adminhtml.xml configuration files. information located in config.xml. later versions of magento broke information out adminhtml.xml files, , merged these files other config.xml files when system serving backend admin pages.

the system.xml files not part of global configuration. they're separate system automatically building ui in backend application setting system configuration values.

how magento loads these files long involved tale that's not appropriate stack overflow answer. have four article series covers in detail if you're interested in sort of thing.

the short version config.xml files loaded here

#file: app/code/core/mage/core/model/config.php $this->loadmodulesconfiguration(array('config.xml',$resourceconfig), $this); 

the adminhtml.xml files loaded here

#file: app/code/core/mage/admin/model/config.php mage::getconfig()->loadmodulesconfiguration('adminhtml.xml', $adminhtmlconfig); 

and system.xml files loaded here

#file: app/code/core/mage/adminhtml/model/config.php $config = mage::getconfig()->loadmodulesconfiguration('system.xml') ->applyextends();