Re: A float has ice cream in it . . . EXCEPT
...when the carbonated beverage is seltzer water from the tap at the fountain, flavored with fountain syrup, with ice cream added. Now that is an ice cream soda.
Inexplicably, a float made of vanilla ice cream in ginger ale was called a "farmer soda".
At home in upstate NY, soda is a carbonated drink, no matter what its package, but growing up I heard "soft drinks" more than "soda" and never heard "pop", except as part of an ancient song sung as a round, entitled "Fish & Chips & Vinegar" (which we kids didn't understand. Vinegar???).
The bass part of the song went:
"One bottle-a pop, two bottle-a pop, three bottle-a pop, four bottle-a pop, five bottle-a pop, six bottle-a pop, seven bottle-a pop, pop."
Regards--
Mary Anne