I'm sure they're not lying. That's what they think it is. Not everybody that works at an orchid growing facility is knowledgeable, though.
Just like you don't want to take the word of all the staff at a nursery. Some of them are just workers.
My favorite orchids book says "Dendrobiums of the section Phalaenanthe are usually referred to as Phalaenopsis type". They need a lot more light than Phals and less moisture. You don't want to assume that one type of orchid is related to another because their care can be drastically different. There are many thousands of kinds of orchids.