Glass Screen Replacement VS. LCD & Touch Repair
To the left are some pictures that will help you differentiate between if you need a screen replacement for just a cracked or shattered glass, an LCD or both.
Screen Replacment Replacment
The screen replacement refers to when jut the glass is cracked. The underlying picture should be perfect with no blines, blotches, pressure points, or off color. Touch should respond 100% even though the glass is cracked./p>
LCD Replacement Replacement
If the image has any imperfection, then you need the LCD replacement repair. This includes but is not limited to: dark spots, no image visible, lines in the picture, discoloration, colors being off, pressure points, white perisitent bright spots, rainbow image, etc. The LCD is what lies beneath the glass and is similar to your LCD TV in your living room.
Even if the picture looks perfect but touch is intermitted or non responsive in some parts of the screen, the LCD would need to be replaced. This is because in iPhones, the digitizer is fused to the LCD. The digitizer is responsible for transcribing analog touch signal into a digital signal. Sometimes when you crack you screen or drop of your phone, the digitizer can break leading no some dead spots in touch or touch not being responsive at all.
Cracked Screen and LCD replacement.
Often times, the glass screen and picture (LCD) will both be dmaged by a fall. If so, you'll notice a cracked glass screen as well as problems in your image.