There really is no difference. Maybe different brands made them. But Land-o-Lakes does make both blue and red caps...
the color
The only difference is the colour of the external shell.
Simple one is a black-red star and the other is black-blue star. The only difference is the color.
Wall thickness
Wavelength Frequency and Photon Energy
Cap color...nothing more.
Red litmus paper will turn blue in the presence of milk, indicating a basic pH. Blue litmus paper will remain blue, as milk is not acidic enough to change its color.
They are not really red and blue. This is seen in preserved animals (and cadavers) and in drawings to show which are higher in oxygen (red) and lower (blue). In general, you also can see than veins are shown in blue and arteries are red.
The difference between a blue nosed pitbull and a red nosed pitbull has nothing to do with their nose it is the colour of their fur and akin. 'Bluenose' pitbulls are grey where as 'Rednose' pitbulls are brown.
They're spelled differently.
The differences between red and blue light are Red stands for n00b and blue stands for b00b! your mum
The red pet means they had a bad life and the blue one means they had a good one. :)