"The best chips are generally binned as higher-end parts, being sold as not only the fastest parts with their full caches enabled, but also the low-voltage and ultra low-voltage models. Note: Based on market demand, these highest-end chips can also be sold as lesser chip parts." - "Chips which do not perform as well as the best chips are often sold for lower clock speed models"
http://www.geek.com/chips/from-sand-to-hand-how-a-cpu-is-made-832492/
"In order to undergo binning, manufactured products require testing. Finished products enter a machine[3][4] that can test hundreds of pieces at a time, taking only a few hours to complete. Each piece can be tested to determine its highest stable clock frequency and accompanying voltage and temperature while running"
https://en.wikipedia.org/wiki/Product_binning
"Another part of it, though, is that Intel fabricates millions of dies for use in all manner of computing platforms. When you deal with those sorts of numbers, the manufactured components are going to have a wide spectrum of performance tolerance, at which point (to increase yield per wafer / ROI) off-spec components are binned into higher/lower spec products. If Intel has a bin filled with underperforming dies that "didn't make the cut" for a high-end product, they can increase yield-per-wafer by shipping those in lower-end products that don't require the same level of performance.
Intel's spec for K-SKU processors demands higher thermal, frequency, and voltage tolerance than—for instance—their power-saving S-line. In general, this means that consumers purchasing K-SKU products will have an objectively "better" die housed under their IHS, being that it's been tested and qualified for more abusive computing environments. Intel knows their K-SKU devices will be marketed to overclockers, and thus selectively uses higher-quality components for them."
http://www.gamersnexus.net/guides/1140-silicon-die-bin-out-process-explained
Binning doesn't always mean higher vs lower quality. Binning is 'sorting'. It can be based on any number of criteria. Stability, raw speed, min power consumption etc. I would imagine cpu's go through several phases of production, where so long as it's haswell for instance, an i3/i5/i7 may go through similar phases. Then at the ht phase, i3's, i7's and xeons go through a common process and i5's skip that step. For igpu's, i5's, i7's and some xeons will go through that step and other xeons won't.
As far as one product being more 'durable' than another, some of it is marketing. I can take the same identical part as a consumer grade and call it 'enterprise' by slapping an extended warranty on it and charging more. Doesn't necessarily mean it's different. Perfect example, gigabyte motherboards. The ud5h and ud3h both have a 'black edition'. The black edition costs more money than the non black edition. They are 'certified' that they go through 168hrs of testing (exactly 7 days) prior to being packaged and shipped. They also come with a 5yr warranty vs 3yr warranty.
Aside from the color schemes, the products are identical. Just because one was tested and passed doesn't mean a non tested one won't pass, that assumption can't be made. So someone can say yes, but they're extending the warranty of usefulness so they must be confident in that part.
They don't have to be, warranty costs are factored into every product. Like auto insurance, everyone pays, few will actually need to draw on it and it can actually be a revenue stream for the company. In addition they charge more. Most people aren't returning the mainstream model, much less the bk edition - for those that do, no skin of gigabyte's nose, they've collected enough extra to just pack up and ship out another board.
In the case of xeons, they're touted as being durable or more durable - than what? How many people, many of which use their cpus constantly, leave them powered on, running torrents, serving files, running a plethora of @home type software that's constantly computing - have had a plain old desktop chip just wear out? In a sense it's marketing to sell at a higher price with no proven sense of need or urgency. And if a xeon did die, they've already collected so much extra profit from all their chips intel won't miss even a $2000 high end xeon. Simply slap a stamp on it. Not to say chips can't fail, anything can fail. But it's already a rarely seen phenomena in the 'boring ol retail' market much less the workstation arena. I also highly doubt these workstation chips are server grade, not many are going to put a 1231v3 in a heavy duty server. That's what the $2-3k 8-12+ core xeons are for.