What is the difference between Alif and Hamzah? Can you please explain the differences and their usage model?
Jazak Allah
Answer
The true alif is a saakin letter after a fathah
, as in the word 
: Some list the letter alif as
in the Arabic alphabet as to make clear that it is always preceded by a fathah and is always saakin. The regular hamzah
is a letter that looks like the head of the letter 
and is pronounced from the deepest part of the throat. It can be written over or below different letters as a holding place for the hamzah, not part of the letter. One of the letters the hamzah can "sit" on is the alif, such as in: 
, or it can be written on a ya': 
, or a 
as in: 
. It can be written on a "tooth" demonstrated in the word: 
, or have no particular place to rest: 
. Please also see: http://www.abouttajweed.com/q240601.htm
Wa iyyaakum