Google's Tango is about the future whereas Apple's ARKit is about the present.
Apple has often been accused of acting like it invented things that others have been doing for years. That complaint is not without merit, however Apple can lay claim to transforming existing things into mainstream successes, which takes no small amount of invention in its own right. Fingerprint authentication and contactless payments are just two recent examples, having both existed in Japan and on niche devices for over a decade before Apple raised them to global prominence with the iPhone.
Next up on Apple's agenda is augmented reality, the act of superimposing digital data and visuals atop a live video feed of your surroundings — something that Google, Microsoft, and many others have been experimenting with for a long time. Apple is far from being able to claim it invented AR, but its new ARKit in iOS 11 is already showing signs to suggest that Apple will help bring AR into the mainstream faster and better than anyone else. Read More at The Verge