The Orange Pi One is the most recent SBC from Xunlong. It's clearly the Orange Pi PC's little sibling. In case you haven't read the PC's review already maybe it's time to do it now since here only important differences will be shown.
Since it's based on an Allwinner SoC (system on chip) please keep in mind that you will always find the most comprehensive and up-to-date information in the linux-sunxi wiki: http://linux-sunxi.org/Orange_Pi_One
The most important differences between One and