When it is mixed with lemonade or lemon flavored beverages, it is called a “shandy” while a radler can use any citrus-based beverage (grapefruit is very common, for example)
But like most styles of beer, diffrent breweries can play a little loose with what they call “shandys” or “radlers”…a lot of it can geographic. WI almost exclusively refers to them as “shandys” for example.