Comics tagged with "New series" are Webtoon premium comics, they're exclusive to webtoon and the creators have a contract with Webtoon and are payed too, so webtoon will always promote all new premium comics by putting them on the banner.
The banner has a mixture of premium and discover comics on the banner and front page so I can see how that's confusing. You can tell if a comic is in discover or premium by looking at banner when you click on the comic, if you can see the stats (views, subs, etc) then it's a discover comic.