Air carrier pilot flying reported DTW taxiway signage is difficult to see and led to the flight crew passing the instructed taxiway. The reporter also noticed there was a discrepancy on the AMM in the Jeppesen charts and taxiway charts; which contributed to the confusion.

Narrative

We were at the north terminal area ready for taxi instructions for takeoff. The instructions were to taxi K; K9; Y; hold short Taxiway B. We briefed the route; read it back; and both said that we expect the first right turn followed by the first left turn to go down to Taxiway B. However; a discrepancy on our Airport Moving Map (AMM) in the Jeppesen charts shows what looks like a concrete island in between Y and K and Y9/Y10. Furthermore; the signage on the ground was showing Y9 and we did not see K9. So; we confused the actual concrete island that exists between K8 and K9 for one that we expected to exist between K9 and Y10. As we moved along we passed K9. Ground quickly noticed and rectified our taxi by instructing a turn onto K8 to get back on track.Causal factor is the signage for Y9 and K9 from our taxi out location being hard to see. Y9 was very visible but nothing for K9; and it makes it a bit tricky now seeing that K9 becomes Y9 or vice versa. The AMM would also be more of a help if it did not outline the taxiway areas as having gaps in pavement; which the taxiway chart does not show. The depiction seems as though it is not all paved the same; but it is. The chart page is more accurate in this case.