To add to @Tanisha's reply, LINE Webtoon offers two "ways" to read comics.
First off, is the Featured section. When you stop by the main page of LINE, and see comics like the ones you've listed above, you're seeing the comics that are paid to publish on LINE. These are series that are generally very popular and LINE is willing to pay to get their content on a regular basis (a schedule which LINE sets for creators - so some series post every Wednesday, some series post every day, it's sorta like a neat TV guide for comics and the creators are paid to update on their specific days).
Then there's the Discover section. Discover is where you and other creators who are posting for free - and not getting paid by LINE - post and showcase your work. These comics do not get featured on the front page, though there are popular sections/trending/etc. respective to the Discover section ( just not on the front page).
Only Featured comics on the front page that are paid to be featured get fancier banners with more of a polished work, simply to give the front page a more unified look.