high horse vs attitude

high horse and attitude both are nouns.

Word	Noun	Adjective	Verb	Adverb
high horse	Yes	No	No	No
attitude	Yes	No	No	No

As nouns, attitude is a hypernym of high horse; that is, attitude is a word with a broader meaning than high horse:

high horse: an attitude of arrogant superiority
attitude: a complex mental state involving beliefs and feelings and values and dispositions to act in certain ways

Other hypernyms of high horse include mental attitude.

high horse (noun)	attitude (noun)
an attitude of arrogant superiority	a theatrical pose created for effect
	the arrangement of the body and its limbs
	a complex mental state involving beliefs and feelings and values and dispositions to act in certain ways
	position of aircraft or spacecraft relative to a frame of reference (the horizon or direction of motion)