Hieee...Mylo.....
I have taken your two originals and measure up its histogram for both faces and its profile is equal(use photoshop....do selection with the rectangle tool and with the selection active, look at the Image->Adjust->Levels....
Both the photos selected face "levels" profile is identical. However, the only difference in this case, which may have introduced a slight difference in brightness of the photo is the "glare" area of the top photo which is more.(I have compared the differences in the framing and subjects in theframe and shade it - you see that the subjects in the "frame difference " area ,in this case your photo -are things which have significance influence on the overall photo.
Looks like the color difference is solely due to the Auto White balance(if this was what you have selected). OR.....inconsistency in your IMAGER(sensor) in reproduction of colors(which is less likely).....
1).......try taking some photos of a subject......repeatedly on a Tripod (same frame) and see if it is consistent......metering on same location.
.2)......try taking some photos of a subject......repeatedly on a Tripod (slight shift frame left/right like your photos above) and see if it is consistent......metering on same location.
3) ......Next try with different white balance with the same setup and see the results....
THis will help you characterize your camera and you will learn to adapt to its behaviour and make your photographs more predictable...
Hope these inputs did answer part of your question....
regards,
me