Developing nations and Developing country

Developing country and developing nations are semantically related In some cases you can replace phrase "Developing country" with "Developing nations", this phrases are similar.

Developing country noun - A country that is poor and whose citizens are mostly agricultural workers but that wants to become more advanced socially and economically.

Developing nations and developing country are semantically related in underdeveloped countries topic. You can use "Developing nations" instead a noun phrase "Developing country".