ULSD is the only diesel available in the USA. If you want pure diesel fuel, it will be ULSD.
Bio-diesel is a generic term for any diesel fuel that is all or part made from biologic (organic) sources rather than petroleum. If it is a mix of organic and petroleum, it will have a number such as B10, which means it is 10% bio (organic) and 90% petroleum-based. B20 is 20%, etc. Some people make their own diesel from 100% biologic (organic) sources, e.g. recycled cooking oils, but these have limits on general use.
If bio-diesel is sold at a fuel station, it still must meet the ULSD spec. It is sometimes called Bio-ULSD or Bio-diesel-ULSD.
If the engine in your 2007 coach was produced after 1/1/2007, then it MUST use only ULSD, whether 100% petroleum or Bio-ULSD. If the engne is pre 2007 production, then it can use LSD or ULSD diesel, petroleum or bio. I believe Cummins now approves use of B10 and B20 bio-fuels, but not a greater percentage of biologics in the diesel.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL