McDonald's is trying to compete with Starbucks' biggest advantage — here's who comes out on top (MCD, SBUX)

• McDonald's and Starbucks are making major investments in mobile ordering apps. 
• As foot traffic falls, chains are growing sales by convincing customers to order on their smartphones. 
• We tried both McDonald's and Starbucks' mobile apps — and discovered McDonald's is catching up to Starbucks' digital domination. 

As foot traffic falls flat, chains are turning to mobile ordering in an attempt to boost sales. 

The number of orders being placed via mobile apps skyrocketed by 50% in US restaurants in 2017, according to data from the NPD Group. And, Business Insider Intelligence predicts that by 2020, mobile order-ahead will account for 10.7% of all quick-service restaurant (QSR) sales.

So far, Starbucks has led the way in mobile order and pay. Mobile and other digital payments make up nearly a third of all of the coffee chain's sales, and they account for even more of the company's sales growth. 

"Almost all of our same-store sales growth is from those customers that we have digital relationships with and those that are in our Starbucks Rewards program," Starbucks CFO Scott Maw said at a JPMorgan forum in March. 

Seeing Starbucks' success, other chains are trying to cash in on mobile ordering. In 2017, McDonald's announced plans to roll out mobile ordering at all US locations. 

However, while mobile orders are intended to make ordering more convenient for customers, they can also create new issues. Starbucks has faced problems with overcrowding and bottlenecks in the past, though these seem to have been resolved with some behind-the-scenes changes. 

With McDonald's building out its more gourmet coffee offerings and Starbucks working to improve its food selection, the two biggest chains in the US by sales are competing more and more. So, we decided to see how their mobile-ordering apps measure up. 

Here's how the Starbucks and McDonald's mobile ordering experiences compare:

SEE ALSO: Starbucks just quietly made a change that reveals the future of the company — here's how it works

Starbucks has spent the last few years perfecting its mobile order-and-pay system.

Starbucks' most recent app update made it possible for all customers to order using its mobile apps. Previously, only Starbucks Rewards members with money preloaded into their accounts could use the chain's mobile order-and-pay system.

The app interface is sleek and easy to use.

With most sales growth coming from its app, Starbucks needs to make it an enjoyable experience. The company's current CEO, Kevin Johnson, actually came from the tech industry and spent 16 years at Microsoft.

One of the major perks of mobile ordering is customization.

Fewer pumps of flavored syrup? Soy milk instead of two-percent? Extra sugar that you'd be embarrassed to order out loud? Starbucks' app makes it easy to customize, and it helps customers avoid yelling out nitpicky clarifications in a crowded coffee shop.