So it differs from Reddit as Reddit's feed is based made of subreddits that share links creating a unique feed of content while WebArcs's feed is feed of the other feeds of sites you subscribe to.
It differs from an RSS reader in the way we show the content. Most readers such as feedly try to restrict the functionality of the product so people will pay for it and only offer you an easier way to view the sites you already like and so already have a way of accessing.
On WebArcs we try to enable discovery of new feeds you would not view otherwise. This is the hardest thing to get across, I only keep up with hacker news, Reddit, TheMacro, recode and a lot more because I have WebArcs.
It's when you find a new site you wouldn't of kept up with before on WebArcs that you start getting the real value.
tl;dr It's about enableing you to discover new sites you couldn't keep up with otherwise.
Thanks for your question by the way =D