Need Help Differentiating Norway Stamps

I need some help. How do I differentiate Norway Scott B9 & 10 from B29 & 30?

Perfs are different, colors slightly different.

Specifically, how are the perfs different? Thanks!

B9 and B10 are 13 across the top and 13.5 down the side (according to Scott...I didn't check Facit).

I should have added those numbers, but they are prominently displayed in Scott.

OK, mystery solved. Scott is incorrect. I checked Yvert & Tellier and the difference is wartermark. B8 & 9 are watermarked.

Typo, I meant B9 & 10.

Unless someone checks first, I'll try to remember to check Facit this evening.

From Facit,
1st set, #184-185, perf 13 x 13½, watermark Posthorn.
2nd set, #187-188, perf 13 x 13, no watermark.

Facit lists both as printed in red and blue - a lot of good that does LOL LOL.

Scott shows different colors, especially for 30 + 25 ore; deep ultramarine in the first set, and chalky blue in the second set. Sometimes the posthorn watermark is very difficult to see, as it is in the (Norway) Scott #207-219 vs. #220-234.

I've concluded that there is no difference in perfs. The differentiator is the watermark.

Just to flesh out this statement a bit, are you thinking that both issues are compound perfs, or that neither issue has compound perfs?

I'm not sure I understand your question. Both issues have the same perfs (Top and side).