RT is deployed here on shadows only, and specifically shadows cast by the sun (interior shadows are standard shadow maps - albeit of a higher quality, with decent filtering). RT shadows significantly reduce artefacting issues, eliminates the jarring cut-off points found in shadow cascades where a high quality shadow switches to a much lower quality one at close range and most importantly, the properties of shadows in real life are more accurately rendered. Shadows from small details are retained where often they disappear with shadow maps, the so-called Peter Pan effect. This term describes how light leaks through objects as the area of contact cannot be rendered correctly.
Ray traced shadows do not have this issue and more than that, they accurately display shadow softening: the further a shadow is from the object casting it, the more diffuse the effect. Interestingly, the PC version has Nvidia PCSS shadows - an attempt to simulate this effect - but it is exactly that: an attempt. It was good for its time, but RT gets the job done properly. The RT shadows look good, but do not run at full resolution, which can result in some pop and fizzle. The fidelity mode does not eliminate these issues - rather, it makes the shadows a touch more accurate to the pixel due to the higher output resolution.