An airplane uses the engine to pull the airplane through the air, so lift can
be
created by a less efficient (sic) surface. A sailboat depends on the wind to
provide
the propulsive force, so it is much more difficult.

An aircraft wing is one hell of a lot more efficient at creating lift as
compared to drag than a sailboat sail is. A sail has a pretty miserable L/D
ratio, but a sail doesn't weigh much, it can be shortened for greater wind
speeds, or more sail put up for lesser wind speeds, can be stored easily, costs
less and a whole bunch of other things practical on a sailboat.