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A wing is designed to produce lifting force by virtue of the difference in pressure on each side.
A control surface is designed to produce manoeuvring force by virtue of the difference in pressure on each side
FTFY
gbj_tester-
Indeed. The point of a control surface is that they generally increase or decrease the overall amount of lift of the aerofoil they are attached to (or comprise, in the case of the Typhoon’s foreplane, or a stabilator etc.) by modifying the aerofoil profile/angle of attack.
I’m not aware of any control surfaces that aren’t an aerofoil shape, but even if it was just about reaction due to a surface hitting the air at an angle, that would still be about creating a pressure differential between the lower and upper surfaces.
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I'll give you the benefit of the doubt and assume you're being pedantic, but here's a picture anyway...
Top one will produce a force if it's rotated relative to the oncoming air. Presumably at the expense of significant drag. Any difference in pressure is a consequence.
Bottom one will generate lift at a neutral angle to the airflow, with minimal drag. Difference in pressure is deliberate.
rodan
Brun
I could have a guess at the distinction...
A wing is designed to produce lift by virtue of the difference in pressure on each side.
A control surface simply takes advantage of the reaction to the air hitting it at an angle.
Presumably the Eurofighter's foreplanes fall into the latter. The Piaggio Avanti seems to be a common example of a true canard aircraft, the difference is pretty obvious...
Edit: I guess another difference is that in level flight, the Eurofighter's foreplanes aren't doing anything significant. Looking at the Avanti, without those things at the front it would immediately fall out of the sky.