Indo-Iranian language and Indo-European

Indo-Iranian language noun - The branch of the Indo-European family of languages including the Indic and Iranian language groups.

Indo-European and Indo-Iranian language are semantically related. In some cases you can use "Indo-European" instead a noun phrase "Indo-Iranian language".

Indo-European noun - The family of languages that by 1000 BC were spoken throughout Europe and in parts of southwestern and southern Asia.

Indo-Iranian language and Indo-European are semantically related. Sometimes you can replace phrase "Indo-Iranian language" with "Indo-European", this phrases are similar.