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