The short answer
Expedition wins on consistent V6 turbo power (380 hp standard, 440 hp HO), 9,300 lbs tow capability, Timberline off-road trim, and BlueCruise hands-free. Tahoe wins on engine variety (5.3L V8, 6.2L V8, 3.0L Duramax diesel option), Z71 / RST / High Country trim variety, available Super Cruise, and the Duramax diesel's exceptional fuel economy in the segment. Pick by engine preference (V6 turbo vs V8/diesel) and trim ladder.
Engines
Expedition: 3.5L EcoBoost V6 (380 hp standard) or 3.5L EcoBoost High Output (440 hp). Tahoe: 5.3L V8 (355 hp), 6.2L V8 (420 hp), or 3.0L Duramax I-6 Diesel (305 hp / 495 lb-ft, ~24 mpg combined). Expedition is V6 turbo only; Tahoe has more variety including V8 and diesel.
Towing
Expedition: up to 9,300 lbs tow (HO Heavy Duty Trailer Tow Package). Tahoe: up to 8,400 lbs tow (5.3L V8 with tow package) / 8,200 lbs (6.2L V8). Expedition edges Tahoe on max tow.
Third row and cargo
Expedition: 8-passenger seating standard (40/40 split bench). Standard wheelbase + Max wheelbase (~12" longer for cargo behind row 3). Tahoe: 7-passenger standard (8 with optional 2nd-row bench). Standard wheelbase only — Suburban is the Max equivalent for GM. For long-trip cargo capacity, Expedition Max is the move; Suburban is the GM equivalent.
Off-road
Expedition Timberline: lifted suspension, electronic locking rear diff, all-terrain tires, 33-degree approach angle. Tahoe Z71: lifted suspension, locking rear diff, off-road tires. Comparable spec; both legitimately capable for full-size SUV off-road. Tahoe Z71 has slightly more off-road heritage.
Tech and interior
Expedition: 12-inch SYNC 4 portrait screen on Limited+, BlueCruise hands-free hardware. Tahoe: 17.7-inch screen on top trims, available Super Cruise. Both modern. Tahoe screen is bigger; Expedition tech is more cohesive (BlueCruise is excellent).
Diesel option
Tahoe 3.0L Duramax I-6 Diesel: ~24 mpg combined — best-in-class fuel economy for full-size SUV. No equivalent in Expedition lineup. If high-mileage highway commute matters, Tahoe Duramax is uniquely valuable.
Price
Expedition starts low $60s (XLT). Loaded Platinum / King Ranch ~$85k. Tahoe starts low $60s (LS). Loaded High Country ~$80k+. Comparable price ladders. Tahoe Z71 mid-$70s; Expedition Timberline mid-$70s.
How to decide
Pick Expedition for: V6 EcoBoost High Output power, 9,300 lbs tow, 8-passenger standard, BlueCruise, Timberline off-road. Pick Tahoe for: engine variety (V8 + Duramax diesel), Z71 off-road, 17.7" screen, Suburban as Max-equivalent option. Eugenio at Sunrise Ford handles the Expedition side.