water cabbage vs water lettuce

water cabbage and water lettuce both are nouns.

Word	Noun	Adjective	Verb	Adverb
water cabbage	Yes	No	No	No
water lettuce	Yes	No	No	No

As nouns, water cabbage and water lettuce are synonyms defined as:

water cabbage and water lettuce: pantropical floating plant forming a rosette of wedge-shaped leaves; a widespread weed in rivers and lakes

Other synonyms of water cabbage include pistia, Pistia stratiotes, Pistia stratoites.

water cabbage (noun)	water lettuce (noun)
pantropical floating plant forming a rosette of wedge-shaped leaves; a widespread weed in rivers and lakes	pantropical floating plant forming a rosette of wedge-shaped leaves; a widespread weed in rivers and lakes