On the surface, they have the same grey brick look which has been around since the arrival of the low-power "Gemini Lake" based NUCs.
However, the existing titled NUC8i3BEH, NUC8i5BEH and NUC8i7BEH come with progressively meaner chips. The NUC8i3BEH Core i3, the NUC8i5BEH has a Core i5, and the NUC8i7BEH has a Core i7 chip.
The cases are slightly bigger due to the 28-Watt TDP which also needs a bulker heatsink.
The thinner NUC8i3BEK and NUC8i5BEK, differentiated by lower TDP (15 W) SoCs, lack 2.5-inch drive bays.
They should be in the shops next week.