I am red/green colorblind. I actually knew about this because they tested for it the first time I got glasses, and it came up there. But for years afterward I never really thought about it; I’d be able to tell basically every color and only falter on some that seemed ambiguous to me but others had an easier time distinguishing–but I never ascribed this to colorblindness; I just thought it was I who didn’t know the colors well enough. For both of your examples: pure red and pure green are very clearly, obviously distinct colors. I don’t think peanut butter looks green at all, it’s clearly a shade of light brown. Really, the only way I can describe the difference I see is this page: https://en.wikipedia.org/wiki/Color_blindness#Signs_and_symp.... There’s a picture of a landscape with various colorblindness filters applied to it. The first two images look identical to me.

I can tell you that it's not about knowing my colors, the colors of the apples you linked look as different as white vs black to me. And they would look just as distinct even if I didn't know my colors.

Yep, I would never confuse those two. And I can tell that the images on the “bottom” are somewhat different.

Not the OP, but I'm also R/G color blind and I don't believe I'd have any issues with those extreme versions of R and G. My issues happen with lighter shades.

For instance, 00AA00 and 00BB00 are very hard for me. 00CC00 is about when I start feeling confident I could recognize it as green, but it's be harder if the surface area was fairly small (for example text). On the red side, the recognition issues also extend to about CC0000.

It seems that there are many shades (Pardon the pun) of colour blindness.

I'm R/G colour blind, but I can still see red and green. I have issues when red and green are close to one another or blended though.

It becomes impossible for me to distinguish between what is red and what is green, or where the colours start and end.