outter glass and digitizer are both the same ¬¬ and yes you can replace only the digitizer but IMHO i dont recommend you to change only that part, save some more money and go for the whole piece

EDIT

sorry i hadnt seen your link and please dont be a fool this part WONT BE USEFUL for you you CANT do anything with that, you MUST buy the whole part

REMEMBER outter glass = digitizer