The local steel yard I deal with had to order me a sheet of cold rolled sheet so I could do the bed sides on my truck.I told him I was going to need another sheet to do the floor later but for lack of storage I didnt have a place to keep it. He offered me a sheet of hot rolled instead. are there any major differances in working with either types of steel....
Cold rolled has a smoother finish. By hot rolled,I assume they mean HRPO.(Hot Rolled,Pickled,and Oiled) Plain hot rolled less money but is covered in slag and oxides. Pickling removes the oxides. Generally,they will work about the same for most applications.
When working in my dad's welding shop I was tole the big difference between hot and cold was that cold rolled had more consistent size -- that's why we always got cold rolled rods to make sure they would fit bearings, drilled holes, etc.
Cold rolled...if I have a choice, I will always buy it. no slag=no welding prep. and you can see a sharpie on it. just try not to handle in with bare hands too much. the oils in your hands cause light rust, which leads to other issues.
I recently bought hot rolled stuff for general fab work on my truck, but wished I had got cold rolled. The biggest problem I have is having to clean off the scale before it can be TIG welded. The scale is also quite hard, making it a pain to mark out and also difficult to prep for paint.
I've sent fabrications back because they've used hot rolled. Cold rolled is more expensive, but easy to work with. Hot rolled is normally full of crap. I've polished hot rolled to 600 grit then hit it with a butane torch and watched the oils come up. It polishes lousy, plates, lousy and paints lousy. Spend the extra buck on cold rolled and you'll save it in labor and get a better finish what ever you're doing.
Just as the rest said, use cold rolled. Unkl Ian has it right, you probably are getting HRPO, which is the better choice compared to plain hot rolled. Hot rolled can not get as thin as cold rolled either. Strength is about the same. Cold rolled is better for forming. The surface finish of cold rolled is much better than hot rolled. Cold rolled is made by taking HRPO and then reducing the thickness by cold rolling, meaning at room temp. Hot rolled is done at orange hot temps.