iPhone 8 Plus - Earpiece Speaker

Hi!

Does the iPhone 8 Plus loudspeaker (right / bottom) better in quality than the earpiece (left / up)?

I'm asking this because I noticed that my iPhone does not have the same quality on both speakers.

It seems that the earpiece at louder volumes comes with a considerable distortion. When I'm on a call, using the earpiece at maximum volume next to my ear, I don't notice that kind of distortion.

Can someone explain me? Is that normal?