Difference between Lord Shankar and Shiva

Lord Shankar is a human, husband of Goddess Parvati, father of Lord Kartik & Lord Ganesh. He resides in Himalayas whereas Shiva is the sign of Lord Shankar.

At the beginning there were no species in universe. Most of the parts of the earth were surrounded by water. Lord Vishnu resided in water. While he was sleeping a Lotus flower sprouted from his naval. From the Lotus flower Lord Brahma was born. Lord Brahma then wandered to many parts of the earth to explore it & to also know about himself, like who he exactly is, how & from where did he come, or who made him? What is his role, etc?

To get the answers Lord Brahma prayed for many years. Seeing Lord Brahma’s dedication Lord Vishnu appeared in front of him & said “I’ve created you from my body.” Lord Vishnu also explained to Lord Brahma how & when he did this.

Lord Brahma wasn’t convinced by Lord Vishnu’s explanation. He started arguing with him & a fight started between them.

As both are powerful lords their fight could have destroyed the universe thus to protect the universe Lord Shankar appeared before them as a somewhat oval shaped ling known as Shiva Ling. The Ling’s size was immeasurable. Seeing such a big Ling Lord Brahma & Lord Vishnu stopped their fight. They realized that there is a third person also who is extremely bigger than them.

To know who that third person is Lord Brahma took an avatar of a white swan & flied up to see how tall the Ling is & what is on top of the Ling. Lord Vishnu also took an avatar of a wild boar & started digging the ground to see how deep the Ling is.

Lord Brahma kept flying & Lord Vishnu kept digging but both weren’t able to reach a point to know whatever they wanted.

They both got tired & prayed together in front of the Ling to get their answers. Pleased by their prayers Lord Shankar returned to his real avatar from the Ling i.e. Ling became Lord Shankar. Lord Shankar then gave his introduction to Lord Brahma & Lord Vishnu.