Both delivery and transfer refers to how property can changes hands between two persons.
Delivery is generally used for handing over a property item from one person to another. The property in question may range from a document to goods or even real property.
The process of transferring property is usually used for passing the title of ownership or some other rights to another person.
In summary, it is probably safe to state that delivery refers to the physical aspect of the transaction, actually turning over the property item, for example from the buyer to seller, while transfer signifies the legal aspect of the same transaction.
