One of the differences between Android and iOS that stands out is keyboards. Obviously, some Android phones have physical keyboards while no iOS device does, but another difference is Android’s ability for users to change the on-screen keyboard. iPhone users who want to change the keyboard need to jailbreak their phone. Today’s free Android app at Amazon is SwiftKey X, which is one of several alternate keyboards for Android.

If you have never installed an alternate keyboard on your Android phone, you will find it to be a straight forward process. The SwiftKey X installation guides you through the process of selecting what language to use, enabling the keyboard, and finally selecting it as your input method.

Should you ever want to switch keyboards on an Android phone, simply open an app that has an input field, like Messaging, tap and hold in the input field and then tap Input Method. You will see the different keyboards enabled on your phone for you to use.

Perhaps the main feature that distinguishes SwiftKey is its word prediction. It learns how you type and uses that to predict what word you are going to type next, even before typing the first character of the word. By default the keyboard is configured so that pressing the space bar will always insert a predicted word.

If you use word prediction you will want to pay attention to words that appear immediately above the keyboard. Three words appear, and the word in green and displayed in the middle will be the word that is inserted when you press the space bar. If you don’t pay attention, rapidly type, and press the space bar, you will likely end up with words that you did not intend unless SwiftKey did a perfect job of predicting your typing.

To make SwiftKey act like the default Android keyboard select Rapid for the typing style, and configure the Spacebar to complete the current word. Of course, making SwiftKey act like the default keyboard seems to defeat the point of installing it on your phone, and I find the Android keyboard does a better job of word completion than SwiftKey.

If you opt to use SwiftKey’s word prediction, the app can get a heard start with learning what you normally type by accessing Facebook, Twitter, Gmail, and SMS during the installation process. After you give it permission to access your social network and Gmail accounts the app scans through what you post and adds that information to its database to help word prediction. Providing access to these social network and email accounts is optional.

If you haven’t been happy with the Android keyboard, it is probably worth checking SwiftKey X, available for free today, July 21, 2011, in the Amazon AppStore. Afterword you can buy it for $3.99 either from Amazon or the Android Market.