.38 calibre vs .38-caliber

.38 calibre and .38-caliber both are adjectives.

Word	Noun	Adjective	Verb	Adverb
.38 calibre	No	Yes	No	No
.38-caliber	No	Yes	No	No

As adjectives, .38 calibre and .38-caliber are synonyms defined as:

.38 calibre and .38-caliber: of or relating to the bore of a gun (or its ammunition) that measures thirty-eight hundredths of an inch in diameter

Other synonyms of .38 calibre include .38-calibre, .38 caliber.

.38 calibre (adjective)	.38-caliber (adjective)
of or relating to the bore of a gun (or its ammunition) that measures thirty-eight hundredths of an inch in diameter	of or relating to the bore of a gun (or its ammunition) that measures thirty-eight hundredths of an inch in diameter