rough sledding vs hard time

rough sledding and hard time both are nouns.

Word	Noun	Adjective	Verb	Adverb
rough sledding	Yes	No	No	No
hard time	Yes	No	No	No

As nouns, rough sledding and hard time are synonyms defined as:

rough sledding and hard time: a difficulty that can be overcome with effort

rough sledding (noun)	hard time (noun)
a difficulty that can be overcome with effort	a difficulty that can be overcome with effort
	a term served in a maximum security prison