smashing vs shattering

smashing and shattering both are nouns.

Word	Noun	Adjective	Verb	Adverb
smashing	Yes	Yes	No	No
shattering	Yes	Yes	No	No

As nouns, smashing and shattering are synonyms defined as:

smashing and shattering: the act of breaking something into small pieces

smashing (noun)	shattering (noun)
the act of breaking something into small pieces	the act of breaking something into small pieces

smashing (adjective)	shattering (adjective)
excellent	seemingly loud enough to break something; violently rattling or clattering