What is the difference between GVI and DVI? In any maintenance program I found some terms like General Visual Inspection (GVI) or Detail Visual Inspection (DVI) or Detailed Inspection (DTI). I want to know the difference between these types of inspection. 

And which type of inspection is required in which cases.
GVI is general visual inspection and when you make a GVI, you have to be maximum an arm's length distance to the area and/or component you are searching any defects. 

DVI is detailed visual inspection, it depends to the situation but usually you use a tool like a magnifier to inspect the area/component.