sieve tube vs vascular tissue

sieve tube and vascular tissue both are nouns.

Word	Noun	Adjective	Verb	Adverb
sieve tube	Yes	No	No	No
vascular tissue	Yes	No	No	No

As nouns, vascular tissue is a hypernym of sieve tube; that is, vascular tissue is a word with a broader meaning than sieve tube:

sieve tube: tube formed by cells joined end-to-end through which nutrients flow in flowering plants and brown algae
vascular tissue: tissue that conducts water and nutrients through the plant body in higher plants

sieve tube (noun)	vascular tissue (noun)
tube formed by cells joined end-to-end through which nutrients flow in flowering plants and brown algae	tissue that conducts water and nutrients through the plant body in higher plants