The difference between Cookie sheet and Pan

Cookie sheet as a noun (cooking):

A wide, flat metal pan suitable for baking in an oven.

Pan as a noun:

A wide, flat receptacle used around the house, especially for cooking.

Pan as a noun:

The contents of such a receptacle.

Pan as a noun:

A cylindrical receptacle about as tall as it is wide, with one long handle, usually made of metal, used for cooking in the home.

Pan as a noun (Ireland):

A deep plastic receptacle, used for washing or food preparation; a basin.

Pan as a noun:

A wide receptacle in which gold grains are separated from gravel by washing the contents with water.

Pan as a noun (geography):

a specific type of lake, natural depression or basin. They are sometimes associated with desert areas.

Pan as a noun:

Strong adverse criticism.

Pan as a noun:

A loaf of bread.

Pan as a noun:

The chamber pot in a close stool; the base of a toilet, consisting of the bowl and its support.

Pan as a noun (slang):

A human face, a mug.

Pan as a noun (roofing):

The bottom flat part of a roofing panel that is between the ribs of the panel.

Pan as a noun:

A closed vessel for boiling or evaporating as part of manufacture; a vacuum pan.

Pan as a noun:

The part of a flintlock that holds the priming.

Pan as a noun:

The skull, considered as a vessel containing the brain; the brainpan.

Pan as a noun (figurative):

The brain, seen as one's intellect

Pan as a noun (carpentry):

A recess, or bed, for the leaf of a hinge.

Pan as a noun:

The hard stratum of earth that lies below the soil; hardpan.

Pan as a verb (transitive):

To wash in a pan (of earth, sand etc. when searching for gold).

Pan as a verb (transitive):

To disparage; to belittle; to put down; to criticise severely.

Pan as a verb (intransitive):

With "out" (to pan out), to turn out well; to be successful.

Pan as a verb (transitive, informal, of a contest):

To one's opposition convincingly.

Pan as a verb (informal):

To a work (like a book, movie, etc.)

Pan as a verb (intransitive):

Of a camera, etc.: to turn horizontally.

Pan as a verb (intransitive, photography):

To move the camera lens angle while continuing to expose the film, enabling a contiguous view and enrichment of context. In still-photography large-group portraits the film usually remains on a horizontal fixed plane as the lens and/or the film holder moves to expose the film laterally. The resulting image may extend a short distance laterally or as great as 360 degrees from the point where the film first began to be exposed.

Pan as a verb (audio):

To spread a sound signal into a new stereo or multichannel sound field, typically giving the impression that it is moving across the sound stage.

Pan as a noun:

Pan as a verb:

To join or fit together; to unite.

Pan as a noun:

A part; a portion.

Pan as a noun (fortifications):

The distance comprised between the angle of the epaule and the flanked angle.

Pan as a noun:

A leaf of gold or silver.

Pan as an adjective (informal):

Pansexual.