treason vs high treason

treason and high treason both are nouns.

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

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

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

Other synonyms of treason include lese majesty.

treason (noun)	high treason (noun)
a crime that undermines the offender's government	a crime that undermines the offender's government
an act of deliberate betrayal
disloyalty by virtue of subversive behavior