Microsoft is planning to finalize Windows 10 later this week, according to sources familiar with company plans. Said personnel have revealed to the media that Microsoft will have final RTM copies of Windows 10 ready before the week ends. The Release To Manufacturer versions of Windows 10 will be shared with partners ahead of public release on July 29.
There's a major difference with Windows 10 RTM, however. This "final" version of the OS will be released to manufacturers with some features not yet implemented. This is due to Microsoft changing Windows to more of a service (Windows as a Service), which will receive major updates, as opposed to brand new releases. Think of RTM as a minor milestone for Windows.
Expect to see a final copy shared with Windows Insiders, before Microsoft rolls out Windows 10 to the general public.
Source: The Verge