Google "has not yet shown they are truly serious," about the enterprise app business, general manager in Microsoft's business division Julia White told the New York Times. "From the outside, they are an advertising company."

Even though Google execs have made some recent noises about making inroads on Microsoft's business-applications turf, the software giant claims it's not breaking a sweat.

Google has increasingly beefed up its enterprise businesses, such as Google Apps and Google Cloud Services, which compete directly with Microsoft. Earlier this week, Google's head of enterprise Amit Singh announced to AllThingsD the company's goal of nabbing 90 percent ofMicrosoft Office users. But, according to Business Insider, only 4 percent of Google's revenue in 2011 came from its enterprise services, while 96 percent came from advertising.

White told the NYT that Office 365 is "on track to be our fastest-growing business." And in order for Google to be a serious competitor, it would have to "provide a quality enterprise experience" in areas like "privacy, data handling and security."

Microsoft, however, apparently has yet to see much revenue from Office 365. According to the Times, most users still prefer the company's older, more familiar Office software.