HTC (as well as most smartphone manufacturers) often uses more than one supplier for the various components. So seeing some variation in the displays and other parts is not unusual. I know on my old One X EVITA, it was known they used 2 different manufacturers for the display.
The HTC letters on the back are actually separate pieces inlaid into the back plate (as far as I can tell, and this has been the case on past HTC phones). So its normal for you to be able to feel them. It could be you just didn't notice before, or the pieces were a little more "flush" with the surface on your old phone and you were able to feel them a little less.
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Phone: AT&T HTC One (M8)
Tablet: Samsung Galaxy Tab Pro 8.4 (WiFi only)