Ok..so this post isn't about the difference between blocks and nodes but about how to make different blocks and different nodes. I am getting myself ramped up on how the drupal system works and have some questions about the "preferred" way of doing things.

First about the blocks.
Currently I have found that the formatting of blocks seems to kept at a fairly high level (in that if you assign blocks to the left side or the right side they all look the same). Is there a preferred way of changing them in the theme so that they look different? I know that there can be changes at the CSS level...and that can do a lot, but I would like my changes to go a bit deeper than that. Eventually I hope to provide local navigation links on the left, and related links on the right. Within the theme (I am modifying xtemplate) I only see one "block" that can be modified...is there a way to add another?

Second, the nodes. I am noticing that the nodes look the same when in their teaser state, as the do within their expanded state. I'd like to make these look different so that the user knows that they are looking at an individual post rather than a list of posts. Will I need to modify the story or node module to create differences which tie into the template? I'd like to make as few changes to the modules and the drupal source as possible, so that i can upgrade i the future.

You can check out the work in progress at http://www.joshc.com/drupal. Please let me know if you have any thoughts or ideas.