It looks like there is overlap. Oddly, it is "äppelsaft" for "apple juice " and "druvsaft" for "grape juice ", but "apelsinjuice" for "orange juice " and "lingondricka" for "lingonberry juice ". "Fruit juice " can be either "frugtsaft" or "frugtjuice".
juice can mean soup, gasoline, fruit juice, electric current or fluids http://en.bab.la/dictionary/english-swedish/juice
saft can mean fruit juice, soup, electric current, fluids, syrup or sap http://en.bab.la/dictionary/swedish-english/saft
From another discussion in this set of lessons: mannekaeng posted
No not really! With "juice" we mean a fruit drink with no artificial ingredients or added sugar. "Saft" on the other hand could be any sweet non carbonated drink!
Hae Zmrzlina. In my case this sentence showed up just after I had to translate "something (? can't remember) and juice" to Swedish. Since I didn't remember having learn the word for juice before, I tried the Icelandic word jus. And it told me it was correct, just with a typo, so "jos". My surprise when this phrase came right after, I translated it to "jos och kaffe" and it told me "WRONG" :D
That's odd, jos seems to be accepted everywhere at least in this lesson. Are you sure you didn't have some other typo?
– That said, the story of the word jos is this: SAOL tried to introduce that spelling as the recommended one – they're usually more careful with being normative, but in this case they tried – but so many people absolutely hated that spelling that they had to give up. Today that spelling is not even in the dictionary anymore. We're only accepting it because it has been in there earlier. I'd really not recommend spelling the word that way, truth is it looks awful to very many native speakers.