this extremely interesting video show state of the art techniques used to fake global illumination without using ray-tracing and compares the result with the ray-traced variant https://youtu.be/CuoER1DwYLY?t=127

long story short moving object color casting light is the main visible difference that cannot be replicated with traditional techniques (like baking the light reflection in the scene at built time, but can be faked convincingly); ray-tracing is also not limited at reflecting elements that are on the scene like what you'd get from screen space reflection, which is less noticeable of an effect but is there if you pay attention and know what to look for.