Can we use headings and <b> for same thing..

Answer 1

I advice you don't create multiple threads so as to reduced spam, you have created a thread on Headings and you got response, so continue on that thread since it is the same headings you are asking question on.

Answer 2

No, we can not use them for the same thing, because Headings are a feature of the font size and width, but the <b> tag indicates that the font is only wide, and Headings are used for titles only because they help in search and keywords, and the crown is not used.
Good luck.