Purely a matter of choice. I'm not sure what the "recycled" option is, but it seems as though it's the same type of stuff they use on decks -- recycled plastic milk, bottles and wood chips.

The teak will be more expensive because of the material. Left to its own, teak will develop a natural gray color. The other option is to engage in an annual or semi-annual maintenance ritual with expensive marine varnish.

Here is a link that might be useful: {{gwi:1523213}}