Difference Between Forum Positng and Blog Commenting

[DavidMichael]

Blog:
Posting or the content is the main purpose, not the commenting.
No - mainly designed for a single user input.

Forums:
Creates a discussion on a particular topic by allowing commenting of posts.
Yes - forums are created for discussion between several people.

[aliciagwen]

Forums are considered more safe then blog commenting websites, as they are mostly less moderated and sometimes even not moderated. It is easy to get backlinks from blog commenting whereas forums are moderated well and it is hard to add link in forums. Some forums allow signature links, which can help you in off page seo optimization of your website and you can get backlinks from forums profiles too.