Usually misconceptions about inverted flight are symptomatic
of deeper misconceptions about the basic lift-producing
process.
Are their wings shaped differently?
No, to first order, not differently.(*)
Approximately any plane in the world will fly upside down.
Some of them are /optimized/ for flying upside down, but
that consists mostly(*) of things unrelated to airflow,
things like:
-- four-point or ive-point seat belts
-- flop tubes in the fuel tanks, so that the engine
doesn't quit during extended inverted flight
-- stronger structure to handle stresses in funny
directions
-- extra windows for looking out in funny directions
-- et cetera.
Twenty years ago I would have added to that list "fuel
injectors instead of carburetor" but nowadays almost
everything bigger than a walk-behind lawn mower is fuel
injected. Stihl makes a fuel-injected chainsaw.
(*) If you care about Nth order correction terms, some
aerobatic aircraft have less washout and/or less camber,
to optimize the inverted stall. However, not even all
of them do that. The C-150 Aerobat has /exactly/ the
same wing as the regular C-150.