There are two measures of speed in aviation, ground speed, which is the numbers you are all quoting, which include the velocity of the aircraft plus or minus the wind, depending on the direction of the wind.

Then there is what is known as "true air speed" which is what the specs in the post above referred to. This is the air speed of the ship regardless of the wind. This is a critical piece of data because the a/c's capacities are defined according to true airspeed, not ground speed.

All commercials airliners fly considerably below their maximum true air speed which is not safe to operate at for extended periods of time either structurally or mechanically.