Some information about the various platforms:
- Android:
- Programming Language: Java
- Platform: A subset of the Java API plus Android-specific APIs
- Development Environment: Either commandline or Eclipse on Windows, Mac, or Linux
- Devices: Handsets from multiple manufacturers
- Licensing: Fully open source
- Deployment: However you choose
- Marketshare: According to recent reports, in 2nd place (behind Blackberry)
- iPhone:
- Programming Language: Objective-C
- Platform: CocoaTouch (A set of frameworks/libraries written in Objective-C)
- Development Environment: Xcode Developer Tools and iPhone SDK on Mac, only
- Devices: iPhone, iPad
- Licensing: Proprietary
- Deployment: Through the iTunes App Store (approval plus $100/yr required)
- Marketshare: According to recent reports, in 3rd place (behind Android)
Note that market share is subject to change and that Android and iPhone are currently quite close. Now, as for your question about entering the IT industry....
For entering the IT industry, you should really learn the basics of computer software engineering, first, and you should familiarize yourself with common industry-grade programming languages. If you take a look at Programming Language Popularity, you can see that Java, C++, and Python are all consistently ranked highly. I suggest that you start off with those languages. Once you are comfortable with those languages on a standard desktop platform, only then should you consider mobile app development. If you already know Java, then developing both for J2ME and Android should be easy. Note, though, that J2ME is much more limited in functionality than Android (Android supports a larger subset of the Java APIs than J2ME), and Android is most likely going to end up in a second or first place position in the mobile phone market (they recently overtook iPhone and are currently behind Blackberry as of this writing). If you are familiar with C and C++, then learning Objective-C and programming the iPhone is not too difficult, either. Note, though, that you need a Mac to develop for the iPhone. There are many similarities between C++, Java, and Python, so learning one once you understand the others is not all that difficult. For myself, I started with C++, then learned Java, then Python. On my website, I have listed the various online tutorials from which I taught myself C++... those are a pretty good start.