There is a difference but a yet a strong link between the words deen and sharia. Deen means religion, while Shari’a means the laws of Islam. Shari’a are the Islamic laws that govern our way of life, and without it, the deen is incomplete.
What is the source of Shari’a law in Islam? In Islam we are bound by rules formulated by the following:
1. Directly by Allah (Qur’an)
2. By the Prophet or Imams; the Sunnah (Hadith)
3. Mujtahids* (Mujtahid (jurist), capable of inferring and deducing from the religious sources and evidence)
4. Ijma (consensus)
5 Aqal (reasoning and intellect)
*The Mujtahids base their laws from the Qur’an and Hadith, and if an answer is not available there they will go to number 4 and/or 5.
Read more here -> https://www.al-islam.org/islam-faith-practice-history-sayyid-muhammad-rizvi/lesson-21-sharia