Noob question: difference between ROM and RUU

[Zhenya13]

Hey guys,

Just got my CDMA Desire from US Cellular, and before I start attempting to mess with it I want to learn all the basics.

I apologize for the noob question, but after reading the forums for a while I can't figure this out.

What is the difference between ROM and RUU?
The way I understand it ROM is like an OS or the shell of the phone software.
What is RUU? I always see it on the forums as being talked about as a original HTC RUU. Does this mean that RUU is simply the stock ROM made by HTC. I thought that the stock HTC ROM is Sense.

Thanks all

 

[DragosP]

The custom ROM is a colection of software to run properly a electronic device, in our case the phone.
The RUU is the acronym is ROM Update Utility, wich bringing the phone in the initial state: stock rom, stock recovery, stock hboot. And, of course, NO root. Only good for waranty.

 

[CarsnGadgets]

the ROM is basically the android operating system, sense ui, and the standard apps contained in a file that is loaded onto the phone.

RUU as stated above is a Rom Update Utility, an executable file that checks the phone, prepares it and installs the ROM contained within it onto your handset.

 

[Zhenya13]

Thank you guys. This makes it much clearer now.

So if I want to go from 2.1 to Froyo I either need to get a custom ROM or get a Froyo RUU that was built for my Desire - CDMA one?