Magento:: Difference between Mage::getSingleton() and Mage::getModel()

Mage::getSingleton()

Mage::getSingleton() will first check the same class instance is exits or not in memory. If the instance is created then it will return the same object from memory. So Mage::getSingleton() faster then Mage::getModel().

$product1 = Mage::getSingleton('catalog/product');
$product2 = Mage::getSingleton('catalog/product');

$product1 and $product2 both will share same memory of OS and return only one instance each time.

Mage::getgetModel()

Mage::getModel() will create a new instance of an object each time even such object exists in configuration.

$product1 = Mage::getModel('catalog/product');
$product2 = Mage::getModel('catalog/product');

$product1 and $product2 both have different instant of same object and also occupy different memory .