If two sheets of paper are stuck together with glue, the sheets become close to one another. Yet the glue between them is closer to each sheet than the other sheet is.
The illustration clarifies a particular relation of nearness: two things may be close, while the intervening bond is closer to each than the sheets are to each other.
Glue, paper, and physical adhesion are not descriptions of Allah's essence or attributes. The comparison serves only to make a sense of nearness easier to grasp.