For the uninitiated, Intel gives each family of processors a codename. For the most part, these aren't that obvious to the end user since each processor model is given a series of numbers to identify it, such as Intel Core i5 4690K. Here we explain the differences between the Broadwell and Skylake processor families. See also: What is Core M?
If you buy a processor right now, you have a choice of Haswell (which is the fourth generation of the Intel Core processor) or Ivy Bridge (the third generation). You might possibly find some Sandy Bridge CPUs on sale, and these were the second-generation Core chips. You can easily tell which generation a Core i3, i5 or i7 chip is from its first number. So a Core i5 4690K is a fourth-gen part.
Broadwell vs Skylake: What is Broadwell?
Broadwell is the family name for the fifth-generation Core processors, but desktop PC versions aren't yet on sale. In fact, their launch has been delayed from October 2014 until sometime in 2015 - it remains to be seen exactly when you'll be able to buy a PC with a Broadwell chip inside it. Rumours suggest that it will be mid-July to mid-September.
Right now, the only processors based on the Broadwell microarchitecture are the Core M chips in the latest laptops.
Broadwell is a 'tick' in Intel's tick-tock launch schedule. In a tick launch, the current architecture (circuitry) is essentially replicated but using a more advanced manufacturing process. This is also known as a "die shrink" and in this case it's from 22nm (the process used for Haswell) to 14nm.
Moving to a smaller process means the CPU is physically smaller, which also means it uses less power but maintains the same clock frequency, so Broadwell processors should be more power efficient and cooler than their Haswell counterparts. This is good news for laptop users who can expect around 30 percent longer battery life, all else being equal.
Desktop processors will be called Broadwell Unlocked and Broadwell K, and will be aimed at enthusiasts. There will be Core i3, i5 and i7 processors in the Broadwell family, but the very low-end desktop segment will be covered by refreshed Haswell chips.
Unlocked versions will have Intel Iris Pro graphics, the most powerful GPU so far to be integrated into a CPU. It can handle 4K video playback and gaming at 1080p.
For desktop PCs, Broadwell chips will use Socket 1150 and have a 65W TDP. They'll be compatible with 9 Series chipsets including Z97 and H97.
Broadwell vs Skylake: What we know about Skylake
Just a couple of weeks ago at Intel's Capital Global Summit, Kirk Skaugen reaffirmed what had been promised at the company's annual developer forum a couple of months back.
He said that Skylake, the 'tock' which will follow Broadwell's 'tick', is still on track for release in the second half of 2015.
The new Skylake microarchitecture will have a new design, but use the same 14nm manufacturing process as Broadwell. Skaugen said at IDF that Skylake would deliver the expected boost in performance and efficiency.
A demo showed a Skylake processor running in a 2-in-1 laptop / tablet, playing back 4K video. There was even a mention of Skylake's successor, Braswell.
Broadwell vs Skylake: Which is better?
Technically, Skylake is better than Broadwell because it improves on the latter's design and uses the same manufacturing process. This means that portable devices should have better battery life (or maintain the same battery life but be lighter) and more powerful than Broadwell-based devices.
Until we actually see these devices, though, it's impossible to say anything concrete. What's odd is that Intel is still saying that both Broadwell and Skylake chips will go on sale within months of each other which might mean buyers hold off purchases to wait for Skylake. (The roadmap below is the most up-to-date image we could obtain, but is proabably already out of date.)
However, the first available sixth-generation Core processors will be codenamed Skylake-S and will have locked multipliers, so won't be as appealing to enthusiasts wanting to overclock.