If you delete your copy, the original data still exists in the source layer, but you lose your layer configurations. If you change the configuration of your copy of the layer, this does not affect the configuration of the source layer. However, for all of the following layer source types, your layer copy references the data contained in the source layer: No reference to the source layer is maintained. *When you copy a feature collection or map notes layer, the data in the source layer is copied.

The advantage to saving a copy of the layer is you can save configuration changes to your copy and use the copied layer with its altered configuration in other web maps. Be aware that this new layer item still references the source layer.* Save the copy-If you want to make the layer configuration changes available for use in other web maps, save your layer copy.This copy is only available in the web map where you make the copy. This creates a layer in your web map that references the source layer.* Copy-To customize the configuration of a layer without affecting the configuration of the source layer, make a copy of the layer in your web map.If you have privileges to create content, you can save the layer as a new item in My Content, which allows you to take advantage of your layer configuration in other maps. When you create a map that contains a layer owned by someone else, you can make a copy of the layer in your map so that you can configure different properties on the copied layer.

Layer owners (or administrators) define a layer's properties.

Permissions to save webmap