中心 oral ,中央 literally and formal, sometimes specific for something.

中心　is a point.for example,please imagine a circle.it has a central point for drawing the circle　with a pair of compasses.so when we use 中心.we imagine a central point of a circle.then,we figure out only the central point. but, 中央. we imagine a block,or a area. for example,when I was a students,my teachers said to me, ' make a line in 中央' . In that case,we think corners of a ground,after that we make a line in a center area of the ground. so,we can imagine some buildings in a map to hear 中央. I think 中央 is not a point as one target. Like a area,a block. then,we feel a kind of volume from 中央. thanks for your reading! )