Number 1 is used where it is freezing out all the time.
The gell point is pretty much the difference.

Do the truckers still use the ULSD crap same as us? Or do they use a higher sulpher content fuel. Every time I fuel I put in 2-3 oz. of Power Service diesel treatment. It keeps everything cleaned out and lubricated. I still however like to do a biodiesel blend as it lubricates the best.

Here's a link to a Wikipedia Article About Fuel Oil which should give you a pretty clear understanding of our various fuel oils (mainly from a North American perspective). There is some slight misinformation in there, because while Fuel Oil #2 (Home Heating Oil) CAN be basically the same as #2 On-Road / Off-Road Diesel, aside from color, the requirements for Home Heating Oil are dramatically lower than those for on-road diesel #2; the upshot is that you can (practically, not legally) use Off-Road Diesel #2 in your vehicle, but Home Heating Oil will most likely cause problems in relatively short order due to its composition. Also, a link to a Wiki Article On Diesel Fuel. Reasonably good info there as well.

As others have pointed out:

Diesel #2: Standard, On-Or-Off-Road Diesel Fuel.

Diesel #1: Traditionally used to be a blend of Diesel #2 with kerosene / jet fuel. There are different ways of doing this blending, and the agent may not be kerosene. The important point is that it has reduced lubricity, lower energy content, lower gel temp, and lower freezing point than diesel #2. Used for cold weather operation. In many cold-weather fleets and agricultural settings (Northern US and Canada) only Diesel #1 is kept around to simplify logistics chains.

Home Heating Oil: Either Diesel #2 or Diesel #1, with colored dye added, and with fewer environmental and functional regulations on its manufacture. Depending on your area and the refineries supplying that area, it may be virtually identical to Diesel #2; but more likely it will be identical to really old, really crappy Diesel #2 that will damage your vehicle. Burn it in furnaces, not in engines.

Edit: The issue of Low Sulphur Diesel (LSD) vs Ultra Low Sulphur Diesel (ULSD) is another one entirely - it separates types / manufactures of diesel fuels, so there is in fact LSD Diesel #1, LSD Diesel #2, ULSD Diesel #1, ULSD Diesel #2, etc. Only ULSD is presently legal in North America as an On-Road motive fuel - that is to say that if you are filling up at a legal and reputable fuel station, you're getting ULSD, so there's no issue with putting the wrong diesel fuel in your new truck or car.

Low Sulphur Diesel / LSD : 500 Parts Per Million / 0.0005% Sulphur
Ultra Low Sulphur Diesel / ULSD: 15 Parts Per Million / 0.000001% Sulphur

Hope this info is helpful!

From Da Horse's Mouf (a.k.a. The United States Environmental Protection Agency).

More specifically, this PDF Link on US EPA regs for highway diesel:

We are also finalizing standards for NOx and non-methane hydrocarbons (NMHC) of 0.20 g/bhp-hr and 0.14 g/
bhp-hr, respectively. These NOx and NMHC standards will be phased in together between 2007 and 2010, for diesel engines. The phase-in will be on a percentof- sales basis: 50 percent from 2007 to 2009 and 100 percent in 2010.

Also, a separate PDF Link on "Regulations Related to Highway Diesel Fuel in Alaska & U.S. Territories".

Standards/Regulations

This rule will finalize the following:

    * Rural areas (those areas not served by the Federal Aid Highway System) of Alaska will begin transitioning all highway, nonroad,  locomotive, and marine diesel fuel to 15 ppm sulfur content diesel fuel beginning June 1, 2010.
    * 15 ppm sulfur content diesel fuel must be in retail facilities in the rural areas by December 1, 2010.
    * All diesel fuel in Alaska remains exempt from the dyeing requirements in the highway and nonroad final rules.
    * Fuel distributors in urban Alaska will be given the same transition schedule as distributors in the rest of the country for highway diesel fuel.

Benefits of EPA's Technical Amendments

    * Until 2010, rural areas of Alaska will be able to use uncontrolled sulfur content diesel for all uses; and thus will not face the unnecessary burden of trying to carry multiple grades of fuel.
    * All areas of Alaska, including both urban and rural, will begin transitioning both highway and NRLM diesel fuel to 15 ppm sulfur content diesel fuel at the same time: June 1, 2010.
    * Rural Alaska will begin transitioning locomotive and marine diesel fuel to 15 ppm sulfur content fuel beginning June 1, 2010, which is two years earlier than the nonroad diesel final rulemaking requires.

So it would make sense that you saw a percent-of-sales rating for that requirement, as Alaska and other US Territories have different rules than the rest of the ConUS (Continental USA).

Being that I am Canadian, I think that the specific Canadian regs are useful too. So Here they are!

- 15 ppm (ULSD) required for sale in on-road diesel fuel as of October 15, 2006
- 15 ppm (ULSD) required for sale in off-road diesel fuel as of October 1, 2010
- 15 ppm (ULSD) required for sale in all rail / marine diesel fuel as of June 1, 2012