Blog means too personal write ups. We can express anything in a blog and it can be too personal as well. Your thoughts, dreams, travel experience, love, ideas, anything. But Hub is different. Here even though we can write anything, we should control us to keep the writings not to be too personal. Our aim is to educate or make aware a fellow hubber some points. So you need to use a language suiting that purpose. Also take care to keep your contents too personal or self centred. But such types of controls are not there for Blogs, there you can freely open up your mind. So the point is that when you wish to write some very personal things, you just go for blogging. Hope things are clear now.