Okay.
Package Name - This is the lowest level name if you will. Most users will never really see it. They usually look like:
The naming convention is supposed to be TopLevelDomain.SubDomain[x however many].AppName. So lets take one of my apps for example. My website is ayedroid.com and I have an app called Status Via. So it would break down like this:
Top Level Domain - com
Sub Domain - ayedroid
App Name - statusvia
so alltogether my package name is:
If you apply it to a much bigger scale it makes more sense e.g a business in America wants a sales app and their Italian counterparts want the same. Rather than have 2 completely different names they would have
com.businessrus.sales
and
it.businessrus.sales
On the whole it keeps everything much more organised. Additionally, if named correctly you can use the package name to manipulate and take advantage of file structures - although that's not something I know a lot about.
Important to note, you should always use only lowercase for the package name.
Application label - This is simply the text that is shown to the user for your app e.g in the app drawer, in the uninstall menu e.t.c
Windows File Name (.b4a) - This is your project file. It ties together all your bits off code into a lovely package. As you can imagine, it is exclusive to Basic4android but every IDE does something identical.
Application Title Activity Title - This is quite different to the rest of these. It is part of the program rather than the filenames. If you want to change it you can either do it manually in the designer or use:
Activity.Title = "New Title"
I've just realised how long this turned out to be. I hope the wall of text doesn't put you off!