The "green" in green mountains and green waters refers to the color, the green of plants. In other words, the whole mountain is covered with green vegetation. The whole idiom means green mountains and green waters.
And the "clear" in the beautiful scenery means clean and clear. The word means that the mountain looks clear, not foggy. The whole idiom means that the mountains and rivers are very quiet and beautiful, describing the beautiful scenery.
Extended data:
Green mountains and green waters is an idiom, which comes from Songshi Puji's "Five Lights Meeting Yuan": "Q:' What's the matter with the bull's head not seeing the fourth ancestor?" The teacher said:' green mountains and green waters.' Say, "How about seeing you later?" The teacher said,' Green mountains and green rivers.' "
Beautiful scenery is an idiom, which comes from Song and Huang Tingjian's "Moshan gives Hengyang agarwood": "Eyebrows meet, Hunan is beautiful."
References:
Qing-Baidu encyclopedia
Qing-Baidu encyclopedia