Is there just one word, 哈密瓜, for both honeydew melons and cantaloupes?
Honeydew is also known as:


  蜜露甜瓜


which can be shortened to:


  蜜瓜




Wikipedia also proposes the following terms:


罗马甜瓜 (Cantaloupe)
白兰瓜 (Honeydew)


哈密瓜 all the meanwhile is also interchangeable with Hami Melon.

蜜瓜 can also be a term for muskmelons in general.

Chinese is very malleable so YMMV &amp; you might just be better off with something like 绿哈密瓜.