You can get the difference between cart getItemsCount() and getSummaryCount() methods given below:
//Start of code
$productsCount = Mage::helper(‘checkout/cart’)->getItemsCount(); // return cart items count for number of products added.
$productTotalQtyCount = Mage::helper(‘checkout/cart’)->getSummaryCount(); // return cart items count for number of total quantities of products added.
//End of code