package bomb vs letter bomb

package bomb and letter bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
package bomb	Yes	No	No	No
letter bomb	Yes	No	Yes	No

As nouns, package bomb and letter bomb are synonyms defined as:

package bomb and letter bomb: a thin explosive device inside an envelope or package and detonated when opened

Other synonyms of package bomb include parcel bomb.

package bomb (noun)	letter bomb (noun)
a thin explosive device inside an envelope or package and detonated when opened	a thin explosive device inside an envelope or package and detonated when opened

package bomb (verb)	letter bomb (verb)
	send an explosive to