Endurance and Range
Endurance is the measure of how long any aerial vehicle can stay aloft, it is a measure of time (hours, minutes, seconds). Range is how far an aerial vehicle can get on a load of fuel, it is a measure of distance (miles, kilometers, yards and meters).
What is important to realize is that maximizing one by design or by flying style is usually severely decreasing the other. Take the example of a helicopter. The longest endurance is achieved when the copter flies fairly slowly because in this fashion the engine has to power the rotor only to carry its weight, having to produce very little additional power (power is energy per unit time) to push the copter forward. In slow forward flight there also is some benefit of the oncoming air hitting the blades, creating some additional lift without causing problems with asymmetric lift (which happens at higher velocities). This means that it can run at the lowest possible power which burns the least amount of fuel per unit time, maximizing the time it can stay aloft. However, at such a low speed its range is small. Although it can stay aloft a little bit longer flying slowly, while doing so it is not moving all that fast hence not covering a lot of distance. Flying the helicopter at cruising speed optimizes its range, however, the engine in this regime has to provide power for keeping the helicopter aloft AND for pushing it forward rapidly, which takes more power (more energy per unit time) and which it can hence not do for as long as when it flies much more slowly..
For an airplane the longest endurance is achieved near the airplane's stall speed, the speed at which it is just able to maintain its height. At this speed its wing just carries its weight so the power (energy per time unit) that the engine has to generate to push the aircraft forward is lowest in this regime. Since the aircraft under these conditions moves slowly, its range becomes limited. Flying an airplane at cruising speed takes more power, since larger speed induces more friction, however, since the airplane now moves far faster, its range is far larger, even though it cannot stay aloft for nearly as long as it can flying near stall speed.
Both in endurance and range (as well as speed) aircraft far outperform helicopters as flying on a wing is far more efficient that flying on a rotor. The secret is that a wing enables a machine (or animal) to use its power for speed at the same time as it uses it to carry its weight. The air drag that the wing causes, also produces lift and a well designed wing produces far more lift than it causes drag. A rotor turning in a circle does not produce this double benefit.