high treason vs lese majesty

high treason and lese majesty both are nouns.

Word	Noun	Adjective	Verb	Adverb
high treason	Yes	No	No	No
lese majesty	Yes	No	No	No

As nouns, high treason and lese majesty are synonyms defined as:

high treason and lese majesty: a crime that undermines the offender's government

Other synonyms of high treason include treason.

high treason (noun)	lese majesty (noun)
a crime that undermines the offender's government	a crime that undermines the offender's government