迅速 vs 快（近义词）

1)As an adjective both words mean " speedy".迅速 is literary while快 is colloquial.
2)To mean " speedy" ,both 迅速 and 快 can funetion as the predicate ( with a complement sometimes), adverbial, attributive , complement,e.g. :
3)As an adverbial or attributive , 快 is often qualified by the adverb of degree 很，etc. :
4)When meaning " the opposite of"慢 ，with the stress on time saving or short time,快 is used:
5)In the three examples above，迅速 cannot replace 快.
6)The adjective 快 means"sharp".迅速 has no such meaning. e. g. :
7)The adjective 快 also means " forthright, straightforward". 迅速 has no such meaning,e. g :
8)The adjecive 快 also means " delighted" , which cannot be replaced by 迅速. e. g. :
9)The adjective 快 means " nimble"，while 迅速 does not have this meaning.

1)快 as an adv.,mean "hury up,make haste":
2)Meaning " something is going to happen or close to a certain moment".e. g. :
3)In all the examples above ,迅速 cannot replace 快.