Courtesy of BOBISTHEOILGUY.
DINO OIL
Dino oil begins with a base material which is separated from other various crude oil cuts by its boiling range. Various components in crude oil boil off at different temperatures, and material from various ranges goes to a variety of end products such as: kerosene, gasoline, diesel, jet fuel, lube oils, asphalt, etc.
The point being that dino oil base is not a particular chemical species, but a myriad of species, with the only thing in common a similar boiling range. Once this crude cut is split fine enough to be a particular type of lube oil - say automotive engine oil targeted for a particular viscosity range - various additive packages are added. Some of these additive packages are viscosity improvers, corrosion inhibitors and additives to improve filming.
A common process in the refining of crude oil is called "cracking". In this process, big molecules are heated and "cracked" into smaller molecules. The smaller molecules vaporize and are condensed and collected for further processing. When this happens, the various bits left behind can react with each other and form cross-linked molecules, tars, that are resistant to cracking, but are also not good at lubrication. This chemical reaction takes place to oil in your engine. Light components are generated which boil off, and tars are generated and left behind. Eventually the reaction can continue to the point of making varnishes; not like you put on your sailboat, but really heavy junk that solidifies in cooler areas of the engine on various engine parts.
Changing your oil not only removes the acids and other combustion by-products that have collected in the oil, but it also allows for removal of broken down oil.
SYNTHETIC OIL
Synthetic oils are developed in the laboratory- from man made orgainc esters and other synthesized hydrocarbons to provide the exact characteristics desired. These "designer" oils include no impurities, at least when poured from the can. Impurities, of course, can appear during combustion.
Synthetic oil is more expensive because it has to be manufactured rather than just separated from a crude cut.
It can be run for longer periods of time between oil changes because it has better thermal stability. The Mobil 1 commercials where they put dino oil and synthetic oil in pans and cook them until the dino oil breaks down are not hype.
So should you run longer intervals with synthetic oil? Well, there are still going to be acids and other combustion products in the sump over time. These are not removed by a filter. And even the stuff that is removed by the filter will eventually load the filter to the point that its efficiency drops and can go into a bypass mode and stop filtering. Synthetics should still be changed at reasonable intervals unless you use oil analysis.
I must be missing something simple, but I don't get it. I checked the acronym thread, thinking I'd see it there, but NOPE. From all accounts, "dino oil" is what I've always used; Trop Artic, Havoline, Mobil or Motorcraft, whatever is cheapest at the time. 
