Well I had the same two white spots on my 1th N900, after few months the display was gone. The housing was brand new, and the sticker under battery also was saying "MADE IN FINLAND". IMEI number was correct, and so on. But the sticker was like some kid stick it there, and it was diferent to stickers on rest of my devives (one I currently own, and one I sold here on TMO - history of those was clear and true "Made in Korea" used for few hours).
So the one from "FINLAND" had 300+ hours of talk time - imagine that (and where is using / playing if You wish, time).

You have to know, that all "china new" devices are geniuine (I'm not saying anything about funny fake things that only looks like N900 and You'll know they are fake from first boot up), but all of them are refurbished devices with houndreds hours of using behind, or for example minor faults that had been repaired. The whole housing is new, most good quality, or even the same quality as geniuine product.

There is no point in comparing speed, parts, etc. As both Your devices are Nokia's products. The only thing is, one of them was nearly dead, and had whole hosing changed + mayby mUSB reinforced / repaired.

Best way to find out, what's the story behind is scan it with Phoenix sw. Then You will find out few interesting things - like life timer (which can not be changed, and it's counting from new).