The first picture doesn't have a correct white balance. Incorrect white balance in outdoors creates a bluish tint. The photographer should have used a yellowish/orange color filter on the lens, to get maybe about 5600K color temperature to the image to have correct colors.
The shirt looks white, but not whitest white. It's probably very light khaki. In some scenes when there's different lighting it has very mild greyish tint. And some other scenes it looks almost white. Vectorscope would tell the truth.
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