A "run" is a response to an alarm, of any type. The company may not even get to the alarm - as long as they left the firehouse and moved their wheels, they get credit for a run. Conversely, they may respond to one call, leave there and repond the a second call, etc. and eventually return to the firehouse. They may have accumulated four or five runs in total on that one trip.
The term "worker" isn't quite so easy to define. If there was an official FDNY definition for "worker" it would probably be something like this: "a unit arrives on the scene and performs their specific task".
In 1984 a new statistic appeared - Occupied Structural Worker ("OSW"). An OSW is a fire in some kind of structure that usually has occupants. It might be a house, or commercial building (whether there are people in it at the time of the fire, or not). The important distiction is that it is NOT a vacant building.
In the late 1990's FDNY units (usually engines) started to respond to medical calls. The runs and workers statistics include these numbers.
Another new statistic - operating at an all-hands fire, started to appear in the 2010 runs & workers.
Through the years the only constant is runs and workers for engines and trucks. In some years there have been no statistics provided for deputy chiefs (divisions). For most years battalions listed "operational time" (in hours) in lieu of workers.