Directory vs Adverts site question.

Directories


Is there a list of good directories, how many should you submit to?

Is there a certain way which will increase your chances for a certain word?, the "how" side of things.



Also,


What is the difference between a classified adverts website were you submit your websites details and it gets listed, and a directory? is there any difference?

In terms of SEO and if it counts or not as the same thing.

Anyone guys?

For example if we had a submission to Google directory vs gum tree or craigslist.

Is there a difference in essence?