The chinese fans give me a suggestion：
There is no difference between Diamond bow and Emerald bow in essence, just change the color damage and Item durability.
The fan thinks that you can make more changes in different ways such as the trajectory, the speed when arrow fly in the sky, the speed when you pull the bow... so that you can divide bows into different kinds.
The fan says the inspiration is come from a mod which he played years ago called Better Archery

PS the mod's curseforge link
https://www.curseforge.com/minecraft/mc-mods/better-bows
Have a nice day!
————yuwanjun564

Actually there is a difference. It is very small but you can see it in the config file.