Learning Python from Ruby; Differences and Similarities

I know Ruby very well. I believe that I may need to learn Python presently. For those who know both, what concepts are similar between the two, and what are different?

I’m looking for a list similar to a primer I wrote for Learning Lua for JavaScripters: simple things like whitespace significance and looping constructs; the name of nil in Python, and what values are considered “truthy”; is it idiomatic to use the equivalent of map and each , or are mumble somethingaboutlistcomprehensions mumble the norm?

If I get a good variety of answers I’m happy to aggregate them into a community wiki. Or else you all can fight and crib from each other to try to create the one true comprehensive list.

Edit : To be clear, my goal is “proper” and idiomatic Python. If there is a Python equivalent of inject , but nobody uses it because there is a better/different way to achieve the common functionality of iterating a list and accumulating a result along the way, I want to know how you do things. Perhaps I’ll update this question with a list of common goals, how you achieve them in Ruby, and ask what the equivalent is in Python.

http://hyperpolyglot.org/scripting

http://www.rootr.net/rubyfaq-2.html

You will probably have to be more specific, because in terms of design and philosophy there a some huge differences between the two. Python is a lot less complex I guess is the main difference.