The CES technology show in Las Vegas is seemingly all robots, drones and smart gadgets. But its subtext is all about Google versus Amazon.

The two companies are waging war to establish their digital assistants as de facto standards for a new generation of voice-controlled devices. Their struggle underlies many of the product announcements and other events at the show.

Google has plastered digital billboards and the Las Vegas Monorail with ads, announced a new array of gadgets featuring its assistant and sent out an army of sneaker-wearing evangelists to extol its technology at partner booths.

Amazon, which grabbed an early lead in this market, opted for a more subtle approach. Executives from both companies have also been turning up at press conferences held by other companies. –AP