difference between : website theme, skin and layout.

[tiger]

I will be glad if someone explain to me the difference between : website layout, website skin and website theme.
I usually consider all of them as the one thing.

Website Layout:
IS basically tells you how are you going to divide the website. Like how many rows & columns are available. Where are you going to put Ads and also if you are having Google adsense then where you are going to put those ads.

This is actually a layout of the website.

Website Theme/Skin:
For me it is same, no difference between both. It is actually a look. Color schemes. Which makes website with different looks.