14 DAY TRIAL // Microsoft officially released Windows 10 for phones preview to devices enrolled in the Windows Insider program on February 12, but only smartphones that were actually configured to get builds from the fast ring were actually updated.
And yet, it appears that the company also launched the first preview build of Windows 10 for phones for devices that were registered for the slow channel and Gabriel Aul, head of the Windows Insider program, has confirmed this on Twitter.
Basically, there's no difference between the two builds, but the one shipped to slow channel insiders could include a number of fixes that make it a bit more stable.
The slow ring is usually recommended to users who don't want to spend too much time dealing with critical bugs and it includes bugs and fixes for issues that were previously reported by those who got an early build through the fast ring.
Microsoft hasn't yet provided any information on potential changes that could be part of the slow ring release, but in case you have any of the supported devices, which include Lumia 630, 730, and 830, you should now be able to get it without experiencing any issue.
As far as the next build for fast ring users is concerned, do not expect it to ship before March, as Microsoft is trying to release new versions on a monthly basis.