If it looks like you're looking through a broken windshield at a screen you'll just need the glass and not the LCD. If it looks like the image below the glass is all messed up in any part, you'll need an lcd. You should be able to see the liquid part of the lcd seeping out under the screen if that's broken. If it looks fine just order the glass.
Also, if this will be your first time doing this I'd watch some videos. Watch them over and over and over and over. You think I'm kidding, about the repetition but I'm not. Not having actual experience doing this means you'll need to learn as much as you can beforehand. And when you learn it you'll need to be able to remember every little detail. Screws may be different lengths, cables may be a PITA. Please take the time to educate yourself and read read watch watch all you can. I don't want to see you waste the money on glass to break something else.
My first time ever doing an iPhone, I watched a video once and said "oh ez!" When I went to do it, I broke part of the board (namely the clip that held in cable 3), rendering the phone of no use. It looked nice though with the new glass! There was another time I did manage to crack an iPhone lcd while installing a digitizer which was not lack of knowledge, just poor quality of work on my part. Please don't screw yourself.