Much as they did with the Google Nexus 4 last year (remember the small nubs it added to the bottom?), Google and manufacturing partner LG have made some slight modifications to the design of the Google Nexus 5. These were made to address two recurring customer complaints, namely poor speaker quality and rattling power and volume rocker buttons. Both fixes, probably easy to implement on the assembly line, should cut down on customer requests for exchange units. The changes were noted by an Italian Nexus 5 owner who requested an exchange and noticed the subtle differences when he got the replacement unit.
As you can see from the comparison images, the changes are not significant but are noticeable nonetheless. The buttons are now thicker, likely to better fit in the cutouts, and the speaker holes have been enlarged, likely improving sound volume.
Unfortunately, it appears that the user who took these pictures reported that those particular issues but that he was now noticing a “more yellow” display along with stuck green pixels.
LG has also had manufacturing issues with the Google Nexus 5’s camera module. For example, we had to return ours as the camera was unable to focus.
Source : xda-developers