What is the difference between just a regular Digital Camera and the SLR one, what exactly does SLR give u?

a_talis_man described what an SLR quite well.

Also I just want to add that when I jumped to the SLR bandwagon 8 years ago (film SLR), I was amazed by how fast it is compared to my pocket camera. What I mean is the lack of shutter lag which is just feels great.

In time, I began to appreciate an SLR camera even more with its configurability (studio flash) and flexibility (the ability to take pictures just about anytime, anywhere - with the right equipment of course)

SLR gives you
-Interchangable Lenses
-Better quality lenses
-Faster Lenses
-Faster auto-focus
-Better internal electronics
-Hotshoe for external flash(much much better than point and shoot)
-Mirror Lock(not all) which reduces shake
-More customizable(if you know what you are doing)

In addition to what the others said, SLR's are intended for the more serious amatures/professionals. It provides complete creative control over the final image. Also, you are able to switch lenses for different situations, SLR lenses are usually a lot higher quality than the lens in a normal point-and-shoot camera.

Focusing in SLR's is faster and more accurate, especially in darker situations, therefore, it will take a image when your press the shutter.

SLR's are also capable of faster shutter speeds, allowing you to take action photographs, like a person jumping or sports.

And finally, the image quality on an SLR is better that most regular cameras due to a larger sensor.

Downsides:
Lenses can be expensive and you might need a few.
Camera usually more expensive.
Can be too complicated for some people.
SLR's are big and heavy.
Needs a lot of practice to know how to use it well and take good pictures.