When a neutrophil reaches the band stage, the cytoplasm is normally fully granulated and should be identical to its fully mature segmented neutrophil counterpart. The chromatin has continued to condense and should appear as knotted and clumped as a mature neutrophil. When a cell matures from a metamyelocyte to a band, the condensation and indentation of the nucleus reaches the point where all parts of the nucleus are of uniform width. While a U-shaped nucleus is the most classic shape, the band nucleus can be curled or coiled as well.
The cell in the top image to the right is an early band. It has a U-shaped nucleus, but still has a bit of openness to the chromatin texture. As the band moves on to the mature segmented neutrophil stage, the entire nucleus will become quite condensed.
In the second image, there is a late band neutrophil just above the promyelocyte (see red arrow). Observe the increased amount of clumped and condensed chromatin present here. The cytoplasm appears similar to the segmented neutrophils in the same frame. It is also important to note how much more condensed the chromatin becomes in the mature segmented neutrophils, also in this frame.
When it becomes difficult to see if the band has pinched enough to be considered a mature segmented neutrophil, the degree of chromatin condensation and clumping can be used as an additional deciding factor.