bamboo vs giant bamboo

bamboo and giant bamboo both are nouns.

Word	Noun	Adjective	Verb	Adverb
bamboo	Yes	No	No	No
giant bamboo	Yes	No	No	No

As nouns, giant bamboo is a hyponym of bamboo; that is, giant bamboo is a word with a more specific, narrower meaning than bamboo:

bamboo: woody tropical grass having hollow woody stems; mature canes used for construction and furniture
giant bamboo: immense tropical southeast Asian bamboo with tough hollow culms that resemble tree trunks

bamboo (noun)	giant bamboo (noun)
woody tropical grass having hollow woody stems; mature canes used for construction and furniture	immense tropical southeast Asian bamboo with tough hollow culms that resemble tree trunks
the hard woody stems of bamboo plants; used in construction and crafts and fishing poles