Question

What is the difference between where one pronounces the medd (lengthened) letters of alif, wow, and ya’; and when they are leen?  

Answer

The lengthened letters of alif, wow, and ya’ as in the following examples:

 

 

are articulated from the empty space in the throat and mouth (see Tidbit archives: Empty Space in the Throat and Mouth), and have a general area instead of specific, for articulation. 

The leen letters are the wow saakinah with a fat-hah before it, and the ya’ saakinah with a fat-hah before it, such as in: or .  

Alif is not included in the leen letters.  These two leen letters are articulated from the articulation point of the the unlengthened wow point (between the two lips, with a circling of them) and unlengthened ya’ point (the middle of the tongue and what lies opposite to it from the roof of the mouth).