Is there a performance difference between a Dropped Index and a Disabled Index, for a NON-Clustered Index
As documented:

The query optimizer does not consider the disabled index when creating query execution plans. Also, queries that reference the disabled index with a table hint fail.

The index is completely ignored for querying

The index is not maintained while it is disabled.

So it doesn't appear in inserts, updates and deletes.

You cannot create an index that uses the same name as an existing disabled index.

Not documented, but you cannot drop columns that the index depends on.