Is IBM’s $4.4 Billion Cloud Bigger Than Amazon’s? Not Quite.

Is it possible that IBM’s new cloud computing services business unit — the one that got suddenly bigger last year after the acquisition of SoftLayer — is bigger than cloud computing’s dominant player, Amazon Web Services?

It turns out that it is, but it’s not a very good comparison. It all depends on what you consider to be “the cloud.”

Let’s start with the basic numbers, which have emerged in recent days as both IBM and Amazon have reported their fourth-quarter and annual results.

If you look at IBM’s cloud business strictly by revenue, the company’s CFO Martin Schroeter disclosed on a conference call with analysts on Jan. 21 that it finished the year with $4.4 billion in cloud revenue, a 69 percent increase over the prior year.

Compare that with the revenue Amazon reported yesterday in its “other” segment (which includes its AWS cloud unit): $3.7 billion for the 2013 fiscal year. Amazon has never specifically broken out exactly how big AWS is by revenue and so the “other” segment includes AWS as well as revenue from advertising, branded credit cards and other “non-retail activities.”

Now that IBM has said it’s getting serious about cloud services and plans to double the unit’s footprint with $1.2 billion in new capital spending, you can expect Big Blue to argue the point that it’s the player to reckon with. This could erode the perception that Amazon is the king of the cloud, which it has indisputably been for years.

But there’s more to this than a single revenue number. In his comments on the subject, Schroeter specified that of that $4.4 billion in cloud revenue, only $1.7 billion was delivered as services.

The distinction isn’t going to be lost on anyone who has been following the jockeying for mindshare in the cloud business. Schroeter was clear on one point: IBM sees its cloud business as encompassing several things that Amazon simply doesn’t have.

In addition to its public cloud services, IBM is also a big proponent of the private cloud concept, where the customer owns the infrastructure, but has the ability to manage it as though it were a public cloud. It also likes to sell the two together in what it calls a “hybrid cloud.” Its cloud business includes its software-as-a-service offerings, marketing software, collaboration, supply chain management, price optimization and scores of other specialized business apps. IBM also has Watson in its cloud.

So if IBM wants its cloud business to be seen as bigger than Amazon’s, it’s going to be at best a tricky apples-to-oranges comparison. For instance, Amazon doesn’t offer private clouds. Nor does it offer software-as-a-service applications, though lots of companies that build SaaS apps rely on Amazon to host them.

AWS is a pure infrastucture-as-a-service company. And as of last year the market research firm Gartner reckons that to be a $9 billion business. In a survey of the market published in August, Gartner observed that Amazon’s cloud had five times the computing capacity of its 14 nearest competitors combined.

But given that it does some things in cloud computing that Amazon doesn’t do — SaaS applications for one — IBM can and probably will argue that it addresses a wider spectrum of cloud services than Amazon does. In so doing it could claim to lead a market that IBM and only IBM has labeled as “the cloud.” Is IBM’s combined SaaS application business really as big as that of Salesforce, which is expected to crack $4 billion in revenue when it reports in February? Most of that revenue comes from Salesforce’s main product, which is its flagship SaaS software for tracking sales leads.

Analysts have yet to buy in to IBM’s method. Another study by Synergy Research Group looked at the infrastructure- and platform-as-a-service revenue of Amazon versus Google, Microsoft, Salesforce and IBM and found Amazon to be well ahead of the combined revenue of the other four.

That’s not to say IBM can’t or won’t grow. Its plans call for a total of 40 data centers in 15 countries around the world. And it plans to boost its cloud revenue — SaaS and services, all of it — to $7 billion by next year. As anyone who has followed it for awhile can tell you, Big Blue has a pretty good record of hitting its publicly stated goals. But catching up with Amazon on an apples-to-apples, cloud-to-cloud comparison? That’s unlikely to happen in 2015, though you can bet that IBM will find a way to claim the crown just the same.

This article originally appeared on Recode.net.