Could someone explain me the difference, their strong points and weak points?
Hi,
An important difference: PHP is free, .NET not.
There are much more free resources and tutorials to learn php than .net.
PHP can be used on both Linux and Windows systems.
But about technical differences do not know.
I would argue (and it’s just an opinion) that PHP being open source has a much wider audience than does ASP.
That being said, there are far more resource for PHP and supporting communities. Options are good but can also lead to more headaches. Sometimes choices are less than ideal but if you favour flexibility PHP is the clear winner.
Thousands of frameworks/CMS and IDE’s available to you whereas MS bundles the IDE and required tools in a single package. This makes it easier for beginners to get up to speed with all the cool toys. Installing phpUnit on Windows for instance is quite the PITA - but you have SimpleTest and others if you so wish.
It’s really a matter of personal choice but given most tech minded people like choices, the choice seems obvious 
Cheers,
Alex
PHP and .NET are two completely different things.
PHP is a programming language.
.NET is an interface that can run a range of different languages such as VBscript, C#, PHP and more.