I think the crucial difference is that when you talk about "open source X" it means that any aspect of X can be modified as you please. Obviously when you're ta

I think the crucial difference is that when you talk about "open source X" it means that any aspect of X can be modified as you please. Obviously when you're talking about an open source iOS app it's understood that the underlying OS isn't open source. Since there is hardware that is actually open in that sense it's worthwhile to distinguish whether you're talking about open hardware or merely open plans for assembly of closed hardware.