According to below post "Shiva" is different than the "[Lord] Shankara":
Are Lord Shiva and Lord Shankar two different deities?
According to Gita "Shankara" is one of the "Rudra"-s:
10.23 Among the Rudras [Aja, Ekapada, Ahirbudhnya, Pinaki, Aparajita, Tryam-baka, Mahesvara, Vrsakapi, Sambhu, Harana and Isvara. Different Puranas give different lists of eleven names.-Tr,] I am Sankara, ... (Gambhirananda)
However often we see discussions related to these 3, with their names interchangeable. Is this OK?
Are these 3 different entities or 2 of them are same or all are same?
Note: This Qn was earlier asked on Meta, however after learning that this Qn may require scriptures reference, it has been moved to main SE.