Tags vs Categories in WordPress

I’ve not been categorizing my last dozen or so posts. I don’t get what the difference between tagging and categorizing is supposed to be anyway. Maybe if I felt a little bit more retentive about the structure of my blog it would matter. For the most part I just want it to be a linear series of posts. Since most technical articles are outdated within months of their writing, why bother with long time indexing? At least the way categories are implemented in WordPress is a bit of a pain. You actually have to click a series of checkboxes to select your category, or open up a popup box to enter new categories. Whereas adding new tags is just a matter of typing in a series of comma-delimited words into a textbox. So, with tags you have a relatively stream of conscious method of marking up your posts, but categories are clumsy and non-intuitive.