Eva, if you actually are a woman and look remotely close to your avatar picture, I will personaaly take you out and explain the differences between whites and reds for you.
If you are a 325# dude from a trailer park in Whalley, DaveG could probably help you out.
Honestly though, you can check the under the gill plate right near the mout CAREFULLY. Whites will be white and reds will have a peach/pink or red color.
I also tend to find the spot markings on the back of the FRASER whites are much more spread out and fewer of them. Reds seem to have either alot more spots or none.
Whites
Reds
Now it may be just my eyesight messed up from the chronic abuse, but I also seem to notice the reds have blacker mouths.
The Vedder whites are a whole new ball game, they get a distinct green tinge to them once in the system for a while, and they should only be kept if you plan on giving them to someone you want as a future enemy.