Texture unit 0

OpenGL OpenGL: Basic Coding
1

I have a question about multi-texturing and texture unit 0.

Is GL_MODULATE equivalent to GL_REPLACE, but only for texture unit 0?

So, it does not matter if I use any of these lines, as they both give
me the same results for texture unit 0?

glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );

2

Do you enable lighting in your case?
I just thought lighting can be a factor which might make the GL_MODULATE and GL_REPLACE different.

3

Yes, I have lighting enabled.

Now that I think about it, my material color is all white, so perhaps it would seem
that both modulating and replacing look the same.

It will probably look different if I change the color of my material.