Think dots. Let's say you want to make a picture, but instead of lines, you use dots. Each dot is a detail. What if you have three hundred dots, a hundred are light tan, another hundred one tint darker, the last one tint lighter. If you put them together you cease to see the dots. Instead you see someone's nose. Seeing the dots and their different hues are seeing the details, seeing the nose is seeing the big picture.
When I go to the grocery store, I make a point of looking at every price sticker and memorizing how much everything costs. At the check out stand, I add it all up in my head so I know how much it will cost before paying. I think of this as detailed oriented thinking, since I am keeping track of all those items and their prices. Once I glance at a price sticker on a shelf, I commit it immediately to memory. This keeps me from overspending. For some reason, grocery stores are where I memorize best. I zero in on all those prices and nothing keeps me from memorzing them.