Found these pics if it will help. They are basically the exact same tent except the EM has 'D' doors that open to the side, the Copper Spur's doors open down and the Copper Spur is made with lighter materials.
Other than that they are the exact same tent.

The guy at Big Agnes told me that the Emerald Mountain footprint clips would not fit the Copper Spur rain fly clips.
They look the same to me. What do you think?

Copper Spur UL2

Emerald Mountain SL2


Copper Spur UL2


Emerald Mountain SL2


Copper Spur UL2 Footprint

Emerald Mountain SL2 footprint