Forum Moderators: phranque
As to the differences....well...that could be a loaded question.
The reason to choose a language is subjective. What are you comfortable with? What features/functions do you need? What is your hosting environment? Who will be maintaining it after you?
So many variables.
Basically, all do the same thing - produce HTML pages whose content can be dynamic either through includes or database.
It really comes down to which you like better and which serves your needs. I don't recall seeing a chart/comparison between the major scripting languages, but perhaps someone can post a link.