【Instant】 ,  【moment】 ,  【minute】 ,  【second】 ,  【flash】 ,  【jiffy】 ,  【twinkling】 ,  【split second】  are comparable when they mean a particular point of time or a stretch of time of almost imperceptible duration.

【Instant】  and  【moment】 are often used interchangeably, but  【instant】  carries so much stronger a suggestion of infinitely small duration that it is better fitted than  【moment】 for contexts that imply urgency, extreme transiency, or inconceivable swiftness,

【Moment】 , on the other hand, is particularly serviceable when the word or the context carries the implication of a definitely apprehended, even though extremely brief, point of time,

【Minute】  and  【second】  technically apply to measured fractions of an hour, but in the present relation  【minute】 , even more than  【moment】 , suggests an appreciable though short duration of time, and  【second】 , quite as much as  【instant】 , suggests its imperceptible duration.

【Flash】 suggests duration comparable to that of a 【flash】 of lightning; the term is therefore often used when incredible speed in movement, action, or thought is implied.

【Jiffy】  is found chiefly in the phrase in a 【jiffy】 , equivalent to very quickly or directly.

【Twinkling】 , often with an added "of the eye," suggests the quickness of a wink or blink.

Split 【second】 , basically denoting a fractional part of a 【second】 , heightens the implication of brevity as expressed by  【second】 .