There is a difference between a Lord Shiva temple and a Jyotirling. It is said that Lord Shiva himself is present there at all 12 Jyotirlings where as in temples we do establishment( स्थापना)of a Lord Shiva murti as an idol or a shiv linga and start doing prayers and performing all the rituals. No Jyotirling was established by us, it was all already established by Lord Shiva himself.
Each and every Jyotirling has its own importance, google it to get the details as it would be a too long answer to post importance of each jyotirling
Somnath Mallikarjuna Mahakaleshwar Omkareshwar Kedarnath Bhimashankar Vishwanath Trimbakeshwar Baidyanath Nageshvara Rameshwar Grishneshwar