I had posted this before, but it seems appropriate for the thread which has morphed into various Lincoln/Ford differences:
My summary: ONLY speaking to pre 2013 models:
All 2009-2012 MKS have HID, auto hi-beams, power tilt/telescoping wheel, and power rear sunshade. Only some SHO have those features.
All MKS have articulating headlights, not available on SHO
All MKS have LED tail lights
If equipped with a sunroof: MKS has dual sunroofs (one sliding, one fixed) and power dual sunroof sunshades , SHO has one sunroof and the sunroof sunshades are not power
MKS Fob can both lower AND RAISE windows and open and CLOSE sunroof - SHO fob only lowers/opens.
2009-2012 MKS can be dealer programmed to have DRL (uses the foglights), SHO with HID can't
Optional MKS THX II sound is superior to the top optional Sony in the SHO
MKS has the little blind spot mirrors built into the outside driver's and passenger rear view mirrors (unless you have blind side alert), SHO does not have the blind spot mirrors (I don't think...at least not in 2010)
MKS longer warranty
MKS real wood and upscale interior
SHO is lighter
SHO nice grippy suade seat inserts
SHO much wider/better trunk opening/ folding rear seats for trunk access ***** HUGE difference to me****
SHO generally better handling
SHO has a performance Package (PP) option, MKS doesn't
SHO more muscular and "manly" in appearance
Car guys know what an SHO is and gawk, and generally don't know about the MKS Ecoboost