Will, the only difference is the roll mark. The SP and LE are identical in every meaningful sense. Of course roll marks matter to collectors, so there’s that. 
The upper is identical I believe. I believe a few small differences in the lower, such as folding stock used and such.
Wrenches are back for $70 at Arms Unlimited!
https://armsunlimited.com/colt-barrel-nut-wrench-m5-6940-iar-series/
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They were selling that wrench for $50 in early February.
For anyone interested, the LE6940P is available again.
LE6940P - Colt M4 Advanced Law Enforcement Piston Carbine 223/5.56 098289023261 | gun.deals
It’s tough to add any more ARs to the pile these days. 
Thoroghbred had a few of the 14.5 Euro Colts for just over $800. I wanted one so bad. But I already have 5 14.5 ARs.