Lemonade (UK) is the normally term for carbonated water with sugar and some lemon flavouring (although you do hear of 'orange lemonade').The sales of carbonated drinks which would be considered 'Pop' include Lemonade, Orangeade, Limeade etc, also Cola, Dandelion and Burdock, American Cream Soda, Ginger Beer and numerous others.
Soft, non carbonated, drinks are generally referred to as 'juices' or 'squashes'(nothing to do with gourd plants). The difference being (in most cases) that anything labelled 'Juice' is at a drinkable concentration, whereas anything labelled 'Squash' requires dilution (usually about 1:5 squash:water but the label says 'according to taste'). I have known visiting Americans claim they were surprised by the overpowering taste of some of our fruit drinks.
In either case, juice or squash, it is well worth reading the labels, as there are varying degress of sugar added, both for taste and for preservation. And there is a distinct difference between 'Sugar Free' & 'No added sugar'. (the latter implies that sugar contained in the fruit itself has not been extracted)

Nigel