OK lets test this out.

I want to know if I'm the only one that understands the difference between manufacture and build. Please vote truthfully with either Yes or a No if the 5 examples below make sense. Feel free to add a comment if you want.

You build dams, you dont manufacture it.
You manufacture car parts, you build the car from these parts.
You build a house, you dont manufacture it.
You manufacture cement, and use it for building a house.
You manufacture iphone 7 parts, and use it to build an iphone 7.

I ran a custom manufacturing lab for 10 years, I know the difference in manufacture and build as well.

Not to be pedantic though, unless you are building the entire house with cement, the 4th example is wrong.

Then why is someone like BMW known as a Car Manufacturer and not a Car Builder?

The techniques involved in creating a car, and the tech used, lends more towards manufacturing than building.  That's why.

Isn't the difference simply robotics/machinary involved? 

That is the difference that I always noted for the word manufacture. 

Then the OP is wrong...

You are correct.  It does also depend on context such as there are manufactured homes (trailer).  An item "manufactured" was built to be ready-made to serve for "building" purposes.  Might I ask what brought this up?

In a nutshell, pretty much.

The general idea of manufacturing is to create an independent item using technology and/or innovative procedures.  The general idea of building is to use independent items to create a better/stronger/more capable item through any means really.

While the bold is true it isn't the exclusive definition or reasoning for manufacturing.  In the medical device field, you manufacture a ready-made item that doesn't get used for building in the traditional sense.

Though, in my case, I suppose I am building upon someone's biological ability to see.

Also wouldn't build simply be general term (like it could include mass production/manufacturing/construction), the word I think he wants it construct, or construction.