Manual Mode question

Hello all,
I have a newbie question: I finally decided, after having my 60D for over a year, to try manual mode. First of all, I love it!!! I honestly do not know why I waited so long. I love that I have control over so many different variables.
But I digress, I have noticed that I can use a lower ISO speed when I am in manual than when I am in Av mode. For example, I can get the same shot at ISO 200 than I was at 600, 800 or even higher . I noticed that the shutter speed required for a specific aperture is higher in an automatic mode like AV than it is in manual.
Why is this? The answer is probably simple but I just can't wrap my head around it.
Thanks for your input.

I think you have misunderstood something.

You have 3 parameters for controlling exposure: speed, aperture and ISO. If all 3 are the same, whether you got there by using M or Av, the exposure will be the same and the camera will behave the same (e.g., it makes no sense to say: "the shutter speed required for a specific aperture is higher in Av").

Read understanding exposure by Bryan Peterson

Every choice of settings is a compromise: At a given aperture do you go with with higher ISO and faster shutter speed, or lower ISO and longer exposure? The answer depends on whether you are more worried about motion blur or ISO noise.

There isn't necessarily a right answer. You can make choices based on your knowledge of whether you have a tripod, whether your subject will be in motion, etc., but even so different photographers might make different choices.

Now consider that the camera doesn't have the luxury of knowing what you're shooting and under what conditions, so it makes the best choice it can based on what is likely to suffice in most situations.

It's not that it "can't" get the shot that way, but rather it was programmed with different priorities that result in a different choice than what you would have made.

One way to influence its choices is to switch from auto ISO to manual. Or somewhere in your camera's menus you will find an option to limit the range of ISO it will choose when in automatic mode. But the camera will still make its own choices as long as some setting or other is left on automatic.

Jumping into full manual mode without an understanding of the exposure triangle is like jumping into a stick-shift car without anyone showing you how to make it work.

As Jase1125 above indicated, you really need to learn about exposure before you can simply start shooting in manual mode and expect decent results. Here is a good online tutorial about the exposure triangle http://www.cambridgein​colour.com/tutorials/c​amera-exposure.htm

Even though I have many years of 35mm film photography under my belt, I am never afraid to 'cheat' a bit and take a picture on full auto, just to see what the camera chose for the exposure. Then, if I really want to get a different exposure for some reason (such as to get more background shadow detail), I can always use the settings the camera chose and then adjust as appropriate to get what I want.

You can set anything you like in manual mode, but it will not necessarily improve your images.

Pin this over your bed....

Thank you everyone for your input and advice. It is appreciated.