These two tools make the life easier by importing and exporting your old contents from the various Blogging platform to WordPress.
Import option is used when you want to move from other platforms like Blogger, LiveJournal, Tumblr and more or you have WordPress .xml file for your old backups or anything you want to restore.
It requires a proper .xml file and you will see your old contents in your new WordPress site.
Export option is perfect if you want to save a backup of your file locally or want to use existing content on another WordPress site.
This tool will export your posts, pages, comments, custom fields, categories, tags, and more files depend on the theme.
You can simply export one type of file or can export all of them in one .xml file.
The available tools also offer Categories and Tags Converter which help you to convert your categories in tags and Tags in categories.