Saying, saw, adage, proverb, maxim, motto, epigram, aphorism, apothegm can all denote a sententious expression of a general truth.
A saying is a brief current or habitual expression that may be anonymous, traditional, or attributable to a specific source.
A saw is an oft-repeated and usually traditional or old saying.
An adage is a saying given credit by long use and general acceptance.
A proverb is an adage couched, usually, in homely and vividly concrete or figurative phrase.
A maxim offers a general truth, fundamental principle, or rule of conduct often in the form of a proverb.
A motto is usually a maxim or moral aphorism adopted by a person, a society, or an institution as a guiding principle or as a statement of an aim or ideal.
The last three terms, epigram, aphorism, and apothegm, commonly imply known authorship and a conscious literary quality.
An epigram gets its effectiveness from its terseness and a witty turn of phrase; it characteristically presents a paradox or a cleverly pointed antithesis.
An aphorism is a pithy epigram that requires some thought.
An apothegm is a sharply pointed and often startling aphorism such as Johnson’s remark, “Patriotism is the last refuge of a scoundrel.”