What is the difference between blogspot.com and blogger.com ?
Blogspot is the "cloud hosting " solution for blogger sites. If you just want to use the google blog platform and let the site be hosted by your own provider, your blog will not have a domain name blogspot.com but rather yourdomain.xxx. I found an interesting article explaining better the difference here. The summary of that author is "Blogger is a free publishing platform, while Blogspot is a free domain service provider. Blogspot have to be used with Blogger, but Blogger doesn’t have to be used with Blogspot. However, both are designed to work together in providing free blogging experience for their users."
What are the two similar options in the WordPress world ?
When you will read my comments on WordPress in the blogs comparison, you will notice that I tested the two options (hosted or not_hosted by WP). As a result, I have 2 blogs using WordPress content management system. The one hosted by WordPress offers much less functionalities (free) than the one hosted by my provider. Of course, paying a provider does also include cost, if you do not have any yet.
If you opt for hosting by WordPress, your blog will have the address xxx.wordpress.com.
In the second MP test, I installed WordPress Content Management system on a server and used the domain name of that server.
Here is another author's in-depth review of the differences between wp.com free, wp.com upgraded, and self-hosted wp