A primary blog is the one you created when you signed up for Tumblr. It gives you full use of Tumblr’s social features, including follow, like, reply, ask, and submit.
Secondary blogs are any blogs you create in addition to your primary blog. You can create up to 10 of these per day. Secondary blogs can also:
- Be password-protected, if you like
- Have multiple users who can create and manage posts
Secondary blogs cannot, however, follow other blogs, like posts, ask questions to other users, or submit posts to other blogs.