Article and Section are both semantic elements of HTML5. Section is block level generic section of a webpage, but relevant to our webpage content. Article is also block level, but article refers to an individual blog post, a comment, of a webpage.
Both Article and Section should include an heading elements h2-h6.
For a blog post, use following syntax for article and section.
<article role="main">
<h1>Heading 1</h1>
<p>Article Description</p>
<section id="sec1">
<h2>Section Heading</h2>
<p>Section Description</p>
</section>
<section id="sec2">
<h2>Section Heading</h2>
<p>Section Description</p>
</section>
</article>