Written Evidence

An evidence included a letter written evidence or if it meets the following three elements:  
1. Must contain signs reading 
2. Intends to confide or to express one's thoughts. 
3. Deliberately created for use as evidence. 

Deed
Deed is written evidence that the signature and contains the events that form the basis of an engagement, or the basis of a right provided that from the beginning of this deed deliberately made for verification.

So can we find three elements that must be contained in a deed, whether it's authentic deed, and the deed under the hand, namely:
1. There should be a signature. 
2. It contains events that form the basis of an engagement or even become the basis of a right. 
3. It should be made intentionally to proof. 

Deed is divided into two kinds:
authentic deed 
Deed made by or in the presence of the authorities to it.  
Deed under the hand 
Deed which are made available for verification by the parties without any help from the authorities. 

Definition of a letter which is not deed 
Which is included in the letters that are not deed is all written evidence that meets the elements to their written evidence, but did not meet the elements for recognition as a deed.

Source: Asas-Asas Hukum Pembuktian Perdata, Prof. Dr. Achmad Ali, SH., MH.