reckoner vs calculator

reckoner and calculator both are nouns.

Word	Noun	Adjective	Verb	Adverb
reckoner	Yes	No	No	No
calculator	Yes	No	No	No

As nouns, reckoner and calculator are synonyms defined as:

reckoner and calculator: an expert at calculation (or at operating calculating machines)

Other synonyms of reckoner include computer, estimator, figurer.

reckoner (noun)	calculator (noun)
a handbook of tables used to facilitate computation	a small machine that is used for mathematical calculations; can be mechanical or electronic
an expert at calculation (or at operating calculating machines)	an expert at calculation (or at operating calculating machines)