Hard to tell in the water, but whites generally have larger, elongated and more spots on their back and tale. Larger head as well and whites tend to be darker - they don't have as far to travel so are already well on their way through metamorphosis into their spawning stage (also why the reds tend to better quality table fare when caught off the river, in the winter or 100 miles from here there is no difference). Once you have them in the boat you can look behind the gill plate, and the bottom-rear of the collar if there is color you likely have a red. Also, marbles are just whites with a bit of color in the meat as they are able to partially process the orange / red pigment.
In
@sherrett 's post above, before I fully scrolled down it was pretty obvious that the top was likely a red and the bottom a white.
The Columbia River has similar stock with reds spawning in the upper river system and whites in the lower; they refer to them as Up River Brights (URBs) and Tules, respectively. Very similar morphology and there is lots of info online on how to tell the two apart.