Difference two attenuation constant
Although not a proof, this answers the practical significance.

\$10log(α) ≈10log( \dfrac{R}{2Z_0} + \dfrac{GZ_0}{2})\$ becomes the attenuation in dB per unit length for low loss cables for lower RF bands.

To make it more accurate, dielectric constant and thus C reduces slightly in the GHz region and G rises thus loss tangent degradation is a function of dielectric where Teflon is better and air core with foam even better.  The skin effects increase R with rising f and thus the real qualities of coax , striplines become more difficult and critical costs($) rise with bandwidth that spans many decades in the microwave bands.

\$\gamma = \sqrt{(R+jwL)(G+j\omega C)} \$ is the propagation phaseshift of frequency  per unit length which are given by R,G,L,C per unit length.

Both your equations and these are derived from Telegrapher’s equation and Heaviside’s transmission model.