What is the difference between Layer Duplicate and Copy?

[K Tak]

I noticed there are 2 ways to copy layers, one is to duplicate(Cmd+d) and the other is to copy(Cmd+c).

Most of the case,  to duplicate goes well as I hope, while to copy doesn't reflect effect of the original.

But I don't understand exactly what's going on underneath.

Can anyone explain the difference between them?

[Rick Gerard]

I am not sure what you are seeing. If I apply an effect to the layer, add animation, and do anything else to the layer, then select the layer and copy, I get the whole layer with everything intact. The same thing happens when I duplicate a layer. I don't copy and paste layers because it's two keystrokes, Ctrl/Cmnd + c, then Ctrl/Cmnd + v, and Duplicate is just Ctrl/Cmnd + d.

[K Tak]

I should have pasted the actual case, sorry.

https://youtu.be/-ykJ8NxDMCE?t=341

In this scene, it doesn't reflect the effect of the original when using copy (Cmd+c → Cmd+v).

But no problem when using duplicate (Cmd+d). 

So I think there might be difference between them.