What's the difference between ganger and gauger?

Ganger

Definition:

• (n.) One who oversees a gang of workmen.

Example Sentences:

Gauger

Definition:

• (n.) One who gauges; an officer whose business it is to ascertain the contents of casks.

Example Sentences:

• (1) Similar patterns of mortality were seen, although there was a significant excess of thyroid cancer in those employed as pumper-gaugers.
• (2) In 1839 he took a job as Gauger of Salt and Coal, a diurnal round so prosaic that it perhaps fed his increasing flirtation with the fantastic.