Where are you seeing these references? They could mean something different on one platform to the next, but it sounds like Content Section is where the Content Blocks go.
If you can describe a bit more then we can answer better. According to my, I see many times both sections in page builder in WordPress or at another portal which give us page builder facilities. You must have some HTML knowledge to understand it. As I saw in some page builders the content section means the area (ROW) in which you can add contents ..... And in the contents section, you can add content area block according to your ease like 1 block for contents, 2 block for contents or few more. To understand better you can check once Loneyplanet's website footer ..... and can see that there are five content blocks and these five contents blocks are in contents area (Footer area). Appearance can vary according to your CSS. If you think that it's a different answer then .... will request to share more details ...... Like where you see it so we can clear your doubt. Thanks