The word Chai means tea so Chai Tea simply translates to ‘tea tea’. So if you’re referring to it as ‘chai tea’ you’re essentially saying ‘tea tea’. That’s your prerogative, but we think that sounds funny!
‘Masala’ refers to a combination of spices in Indian cuisine; Masala Chai directly translates to ‘spiced tea’ and what most people consider ‘Chai’ to be is actually better known as Masala Chai. Once Masala Chai made its way across various oceans it dropped its first name and become lovingly referred to as just Chai. So really there is no difference, it’s just three different ways to refer to the same thing.