This is a grey area and varies depending on what you read and of course people's perspective.
The most noticeable difference between a blog post and an article is the writing style.
Blogs can range anywhere from 300 to 1000 words, but articles are generally longer pieces of writing. The different nuances to writing a blog and an article will help writers to target their audience in different ways. Generally a blog will have a much more casual style of writing and can be more personal compared to an article which is less biased, may be a but more formal, and is likely to be more informative.
The Homeflow system allows for both styles of writing and has the ability to edit meta data to help with SEO.