Defintion of a transit

Poor article.
I fail to see the definition of a transit.
Case 1 : you fly Hanoi to Guangzhou TRANSIT to LAX. All using one airline (China Southern Airlines).
Case 2 : you fly Kuala Lumpur to Guangzhou with a budge airline eg Air Asia and then have a SEPERATE ticket China Southern Airlines from Guangzhou to LAX.
Is case 2 considered a transit ????