jaeyoungkk , have you made sure that the Rendering Quality in the Main tab of our Visual Settings is all set to the same? For example, Ultra or High? With RTX cards you mostly get better reflections, as in, more elements which are located outside the so called "screenspace" will also be visible in mirror and such, to some extend.
But, there shouldn't be such stark differences like you can see here, I suspect that this may be caused by having different Rendering Quality settings, or material settings applied, so can you also please check that the material is really identical?