glad vs happy

glad is a noun but happy is not a noun.

Word	Noun	Adjective	Verb	Adverb
glad	Yes	Yes	No	No
happy	No	Yes	No	No

As adjectives, glad and happy are synonyms defined as:

glad (noun)	happy (noun)
any of numerous plants of the genus Gladiolus native chiefly to tropical and South Africa having sword-shaped leaves and one-sided spikes of brightly colored funnel-shaped flowers; widely cultivated

glad (adjective)	happy (adjective)
showing or causing joy and pleasure; especially made happy	enjoying or showing or marked by joy or pleasure
cheerful and bright	well expressed and to the point
feeling happy appreciation	marked by good fortune
eagerly disposed to act or to be of service	eagerly disposed to act or to be of service