Persian melon and Sweet melon

Persian melon noun - Any of a variety of muskmelon vines having fruit with a smooth white rind and white or greenish flesh that does not have a musky smell.

Sweet melon and Persian melon are semantically related. In some cases you can use "Sweet melon" instead a noun phrase "Persian melon".

Sweet melon noun - Any of several varieties of vine whose fruit has a netted rind and edible flesh and a musky smell.

Persian melon and sweet melon are semantically related. Sometimes you can replace phrase "Persian melon" with "Sweet melon", this phrases are similar.