Can you tell me what the difference is between pronouncing a Qalqalah letter when stopping and it has a shaddah on it as compared to only having a sukoon.

Question
Assalaamalaikum

Can you tell me what the difference is between pronouncing a Qalqalah letter when stopping and it has a shaddah on it as compared to only having a sukoon.
JazakAllahu Khairan

Answer
Wa alaikum assalaam wa rahmautullahi wa barakatuh.
There is no difference in the qalqaah in both cases because in both cases only one letter has the qalqalah.  When there is a shaddah on a letter, it means there are two of that letter, the first saakin, the second with a vowel.  In the case of a qalqalah letter with a shaddah, the first letter of the shaddah is pronounced with collision of the two components of articulation with no accompanying mouth or jaw movement [like all saakin letters are pronounced]; the second letter of the shaddah of a qalqalah letter is pronounced by separation of the two components of articulation with no accompanying mouth or jaw movement [like all qalqalah letters are pronounced].

Wa iyyaakum.
Wa assalaam