Very interesting observation and something worth checking into. I feel it is good that you have noticed the differences you both share in tying material colors because that tells me that you will probably become very good at tying flies because you are observant. One of the reasons for the differences may be the fishing styles you each have. For instance, one may fish subsurface mostly and the other may fish dry flies or midges mostly. If that is the case, your tying material will be different.

I really do find this thread interesting and will look forward to viewing the responses.

I have to know one thing though. When the two of you do go fishing together, who has the best "catch" ratio? If it is your brother, you may want to switch to the colors he uses! LOL

I honestly feel if you viewed 2 different fly tying benchs, you would probably see that each fly tyer has different tastes, but, that does not mean one is right and the other is wrong. Different strokes for different folks. I find fly tying to be a lot of fun and even more fun when teaching it to others.

Great thread and very good observation which I am sure will be a learning experience for you as you continue to research the differences. I would enjoy being in the same room or on the same river as you and your brother discuss this difference with each other.