Blender - nicely said
Then there is the attitude difference:
In a helicopter, generally,
ATTITUDE=AIRSPEED
POWER=RATE OF DESCENT.
That is, for a given attitude, the airspeed will be fairly constant - choose a 60-knot attitude, and with enough time (attitude is instant, performance takes time) you will have 60 knots. Then, depending on where the power is, you will be in a 60-knot climb, or a 60-knot descent, or level at 60 knots.
In a plank, there is an infinite number of attitudes for an airspeed, and it is only the power setting that governs what you got. Point the nose at the ground, and control airspeed with power, speedbrakes, flaps or whatever.
