Boost is not like a listing site in many ways. To begin, you own your website with NowFloats, whereas on a listing site, you are one of the many businesses listed there. Second, on a listing site, you're exactly that - a listing.
There is little context to your business besides the category you are listed under. With Boost you can give your customers context of your business - with content in form of messages, pictures, deals, subscriptions, enquiry forms, point of contacts, etc.
Lastly, the SEO of a listing site, goes to the listing site. With Boost, when you write your content, it's your website the SEO is going to. You benefit from it first and foremost.