good vs serious

good is a noun but serious is not a noun.

Word	Noun	Adjective	Verb	Adverb
good	Yes	Yes	No	Yes
serious	No	Yes	No	No

As adjectives, good and serious are synonyms defined as:

good (noun)	serious (noun)
a raw material that is sold in large quantities, usually to other businesses for manufacturing or production purposes
benefit
moral excellence or admirableness
that which is pleasing or valuable or useful

good (adjective)	serious (adjective)
having desirable or positive qualities especially those suitable for a thing specified	concerned with work or important matters rather than play or trivialities
morally admirable	completely lacking in playfulness
promoting or enhancing well-being	causing fear or anxiety by threatening great harm
having the normally expected amount	requiring effort or concentration; complex and not easy to answer or solve
with or in a close or intimate relationship	of great consequence
thorough	appealing to the mind
generally admired
resulting favorably
not left to spoil
not forged
tending to promote physical well-being; beneficial to health
in excellent physical condition
appealing to the mind
agreeable or pleasing
exerting force or influence
most suitable or right for a particular purpose
capable of pleasing
deserving of esteem and respect
of moral excellence
having or showing knowledge and skill and aptitude
financially safe

good (adverb)	serious (adverb)
(often used as a combining form) in a good or proper or satisfactory manner or to a high standard (`good' is a nonstandard dialectal variant for `well')
completely and absolutely (`good' is sometimes used informally for `thoroughly')