canicular days vs dog days

canicular days and dog days both are nouns.

Word	Noun	Adjective	Verb	Adverb
canicular days	Yes	No	No	No
dog days	Yes	No	No	No

As nouns, canicular days and dog days are synonyms defined as:

canicular days and dog days: the hot period between early July and early September; a period of inactivity

Other synonyms of canicular days include canicule.

canicular days (noun)	dog days (noun)
the hot period between early July and early September; a period of inactivity	the hot period between early July and early September; a period of inactivity