Google is finally launching its Google Music service at this week's Google I/O developer conference in San Francisco, a year after its reveal at the last event. The new service will be similar to what Amazon launched in March, an online storage locker where your songs will be stored in the "cloud." In this case, the "cloud" refers to Google's servers. Once your music is uploaded, you can stream it to your Android-powered mobile phone or via the Web to your computer.

While both Amazon and Google's offerings have the same basic concept behind their design, there are some notable differences between the two, as detailed below.

Amazon Cloud Drive: 5 GB for Free, Support for Multiple File Types

"Cloud Drive" is the brand name of Amazon's cloud-based streaming music service. Although the focus, at present, is on providing an online home to your MP3 collection, the service already supports other types of files, too, including documents, pictures and videos. In this way, it's more akin to Google's Docs service, because, as with Docs, you can upload almost any of the most commonly-used file types to Amazon's cloud.

The caveat with Amazon's service is the price. You get 5 GB of online storage for free, which equates to around 2,000 songs, assuming you are just using the service for music and nothing else. Anything more, and you have to pay. There are storage plans available with yearly fees attached. These include the following annual plans: 20 GB ($20), 50 GB ($50), 100 GB ($100), 200 GB ($200), 500 GB ($500) and 1,000 GB ($1,000).

However, not only do your Amazon.com MP3 purchases not count towards your storage total, the company is also running a special through the end of the year which allows you to upgrade to the 20 GB plan just for buying one album from Amazon. There's a caveat here as well, that "free" upgrade is only good for one year from the date of the purchase. Afterwards, if you don't sign up to pay for the $20/year 20 GB plan, you'll be automatically downgraded to the free 5 GB plan.

For playing music from your online storage, Amazon's Cloud Drive includes a music streaming service called Amazon Cloud Player. This online app provides basic music controls, playlist support and filters for sorting by Albums, Artists, Genres and Songs. It supports the playback of MP3 files, like those which Amazon itself sells, plus AAC files, like the non-DRM files sold on iTunes. It also supports playlist import from Windows Media Player and iTunes.

The player works on both the Mac and PC platforms, plus Android phones. A somewhat kludgy workaround is available now for iOS devices (iPhone, iPod Touch, iPad), but it's not as polished as the native Android application. It's also not considered an "official" means of streaming your music by Amazon. The company clearly states on its website that "iPad and iPhone are not currently supported platforms for either the Amazon MP3 Store or Amazon Cloud Player." This is mentioned in a side note at the bottom of a chart featuring the Cloud Player's current status for the Web, Android, BlackBerry and Palm mobile operating systems. The fact that iOS didn't even make the chart further hints at Amazon's planned Android-based tablet, reportedly in the works now. By refusing to support iPhone and iPad, Amazon's tablet has a competitive advantage over Apple devices, and Amazon's MP3 store will have a similar advantage over iTunes. (Well, at least until Apple launches "cloud iTunes," that is).

Google Music: Storage for 20,000 Songs for Free, No Music Store

Like Amazon's Cloud Drive offering, Google's Music service is also being launched without the record labels' support. Google's failure to negotiate a proper deal with the labels led to the delay in the launch of Google Music, according to reports.  However, in Google's case, this is a far worse problem than for Amazon because at least Amazon already had a (legal and licensed) online MP3 store where it sells music. Google does not. For end users, that's certainly a shame, but for Google's own purposes, it may not matter as much. Unlike Amazon, Google's main goal isn't to sell more MP3's to end users, it wants to sell Android-based phones. More philosophically, and core to everything Google does, its goal is also to get more people online, using the Web and Google services, all so they can see and click on more ads.

To make up for its missing "store" component, Google is enticing users with features instead. The new service offers things like automatic playlist creation tools and, perhaps more importantly, more free storage. During its initial phase, Google offers beta customers the ability to store up to 20,000 songs for no charge. Google is measuring storage prices in "songs," not GB, for what it's worth. Regardless, Google is offering roughly 10 times the amount of storage as Amazon does, and for free. That's a compelling advantage, and one Google can easily afford. Unfortunately, this "free" option is only available "for a limited time," says Google.

Like Amazon's Cloud Drive, Google Music will involve a lengthy upload process where you use a downloadable client software application installed on your Mac or PC to copy songs from your computer to the cloud. Also like Amazon, a Flash-based Web player will allow you to play your music from your computer, including Google's own Chrome OS operating system. And finally, while Amazon offers a native Cloud Player app for Android, Google will instead update its own Music application for Android, a core app that ships on all Android phones, with support for Google Music. We had previously seen this application in the wild, thanks to users on a popular mobile forum site, XDA-Developers, who discovered a way to install the newer version of the Music app on their phones. They discovered songs could both be streamed and synced to Google's Cloud right from the mobile device itself. Amazon, however, only allows uploads (syncing) from a PC. But both Google and Amazon will support the ability to download songs to your mobile device for offline listening, it appears.

A notable difference between Amazon's Cloud Drive and Google Music is the scope of its offering. While Cloud Drive supports other file types beyond just songs, Google Music, as the name suggests, is for music only. For online storage of other files, Google offers Google Docs, also available as a native Android application.

For now, Google Music will be invite-only - Google I/O attendees will receive invites, as will users of Motorola's Xoom Android-based tablet computer on Verizon, according to TechCrunch.

Geographic Restrictions

Both Amazon's and Google's products are limited to select geographic regions, it should be noted. Currently, Amazon offers Cloud Drive to the U.S., plus Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and the U.K.

At launch, Google Music will be U.S.-only.

Note: This article will be updated after Google's official announcement today. Current sources are AllThingsD andTechCrunch, both of which confirmed these facts with Google.

Image credit: lead - LifeofAndroid; player screenshots, forum user RazorHail