penetrating vs piercing

penetrating and piercing both are adjectives.

Word	Noun	Adjective	Verb	Adverb
penetrating	No	Yes	No	No
piercing	No	Yes	No	No

As adjectives, penetrating and piercing are synonyms defined as:

penetrating and piercing: having or demonstrating ability to recognize or draw fine distinctions

Other synonyms of penetrating include acute, discriminating, incisive, keen, knifelike, penetrative, sharp.

penetrating (adjective)	piercing (adjective)
having or demonstrating ability to recognize or draw fine distinctions	having or demonstrating ability to recognize or draw fine distinctions
tending to penetrate; having the power of entering or piercing	painful as if caused by a sharp instrument