The difference between designer and sales designer

I always like to read through singapore renovation forums. It always updates me with latest design style, supplier and pattern of behavior of renovation happened in Singapore.

Even though I refuse to set my bars following those ID companies pricing. They're really spoil the market specially for designers like me. Because designer is indeed high-worthy job that rules the world's habit, lifestyle and environment.
What makes me feel different from those ID companies are:

1. I'm a pure designer (5 years studied at university for  architecture/interior major), while most of them are just sales designer, whose some even are not from design background.
2. I sketch, draw, draft out the quotation and present those ideas/design to home owner and also coordinate the site management by myself. So I know every details for every corner of the house. While those sales designer usually throw all the design&drawings to their draftperson (whose mostly are freshgraduates from design school) and then throw the site coordination to another person. So when u ask them about small particular stuff of your house renovation, they wouldn't know.
3. Since I'm doing everything all by myself, so I'm limiting myself for maximum of only 3 projects of renovation at the same periode/timeline. Because I want to be able to control those whole 3 projects. While those sales designer are very aiming to get as much as projects as possible for even the same periode/timeline.
4. I design based on existing site condition. My design background had lead me to a pure investigation-minded kind of designer. Meaning that I need to see actual site to be able to come up with design ideas. Because I believe that every space certaintly sending us messages on how they wanted to become in order to fullfill every home owner's habits and lifestyle. While those sales designers are usually work based on floor plan drawings only. No wonder they come up mass design&products. Because sometimes they just following whatever they've seen on magazines, or worst just copy-paste the design from their previous projects.
5. I talk design language. While mostly sales designer are talk sales language. So don't get shocked if I tell you off of some ideas that look nice in the eyes but in reality is not feasible at all, or not practical at all, or just simply doesn't make sense at all. Because I don't like to bluff.

These are just some main points that I can think of. Plenty of difference can be felt once you're facing it for yourself.