Can I say a logarithmic difference is “log-constant”?

I have two variables which vary linearly on a log scale. My understanding is that I can say these are "log-linear."

I'd also like to write that the difference between the lines on a loglog graph is the same across the whole domain. In other words, I have two lines that have the same slope and a constant space between them.

I can think of two ways of saying this, but I'm not sure whether either term will be understood:

1. The difference between the two lines is log-constant.
2. The log-difference between the two lines is constant.

Are "log-difference" and "log-constant" ever used in the literature?

Specifically the difference is not "constant," because e.g. 0.01 - 0.001 != 0.1 - 0.01, however the difference between their logarithms is constant.

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