With Blogger, I got used to tagging my posts to make it easier to find them as part of a category or group. In Blogger, a tag applies only to the blog it’s in. When I click on a tag at the bottom of the post, I get all the posts in that blog that share the tag.
So I started tagging my posts in WordPress. Then, recently, I clicked on a tag on a post and discovered that WordPress tags connect to all the other blogs. Clicking on the tag didn’t show me any of my posts, just posts from other blogs. WordPress “Categories” work more like Blogger tags, linking together related posts within my blog.