Google’s new voice controlled home automation hub, Google Home, has a lot of similarities with its rival, Amazon’s Echo. They both tell you the weather, plays music, and can turn your lights on and off.

But Google Home lacks a critical element: e-commerce. Unlike with Amazon’s hub, Google Home users are unable to use the device to shop, marking a big missed opportunity for the tech giant.

With Amazon’s Echo, you can ask voice assistant Alexa to re-order items you already bought on Amazon’s marketplace or buy any one of its tens of millions of items that are sold on Amazon. The one caveat is that the item must be a Prime product, meaning it is fulfilled by Amazon and can be shipped to shopper’s doorsteps within two days or less.

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E-commerce is an important part of Echo for Amazon because it helps it funnel more of its users’ spending to its online retailing operations by making commerce easier than ordering something through an app. According to a recent Slice Intelligence report, Echo owners are “heavy Amazon purchasers across all categories.” Those who bought an Echo device spent 7% more on items like diapers, toilet paper and other consumer products compared with non-Echo owners. As Slice writes, this increase is “an early, but promising sign for Amazon.”

The ability to order items through Echo also gives Amazon more customer data so it can personalize the commerce experience. For example, Amazon could suggest to customers who are buying diapers, to also buy wipes or other baby items.

A spokesperson for Google confirmed that Home does not currently support “in app payments” that would make e-commerce possible. But the company added that it is “working on bringing that functionality to Home soon.”

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If Google does add e-commerce to Home, it’s unlikely that would integrate with Amazon’s marketplace. Home currently doesn’t allow you to play music fro, Apple or Amazon’s streaming music services. You also can’t access your Google Play Music or YouTube Red subscription services and content easily from Echo.

But don’t hold your breath for Google to add shopping in a way that is as comprehensive as Amazon, said Julie Ask, vice president and principal analyst with market research firm Forrester Research. “E-commerce isn’t Google’s strength. They don’t have consumer purchasing data like Amazon,” she explained. “They need to start with what they know about, which is their users’ daily life.” She said that Google’s advantage is the data it can collect from its users’ day-to-day life from Gmail, Google’s calendar, and the Maps app.

That doesn’t diminish the commerce opportunity for Google. As the company’s spokesperson mentioned, the company is looking to add the ability to make payments through Home. That could mean the ability to order items from third-party e-commerce sites like Walmart or Target. What’s more likely is that you’ll be able to order items from Google Shopping, where users can order groceries from Whole Foods, pet food from PetSmart, and medicine from Walgreens.

“They are going to try,” predicts Ask.