The build number is 14D87p, which is newer build compared to OS X 10.3.3 beta 2 (build number: 14D87h) that was seeded to developers last week.
The new OS X Yosemite 10.10.3 includes the all-new Photos app, which replaces Aperture and iPhoto. In both appearance and features, Photos for OS X is similar to the Photos app bundled in iOS. The two apps share the same approach to photo management with both versions featuring a robust organizer coupled with basic editing tools.
In addition to the Photos app, OS X 10.10.3 also includes a redesigned single-page emoji picker, along will all new emoji and emoji skin tone modifiers. It includes several new people emoji for greater diversity, and 32 new country flags to choose from, which includes flags for countries like Canada, India and others. Apple has also made some changes to better reflect its own products as well, supplanting the existing emoji for “computer” and “watch” with an iMac and Apple Watch, respectively. The emoji for an iPhone reflects an iPhone 6.
Another new striking feature of OS X Yosemite 10.10.3 is that it adds support for Google two-factor authentication. OS X Yosemite 10.10.3 public beta should be available to users who signed up for the beta program through the Mac App Store.