The money that comes from all that work is passive income. Passive income comes from doing work like building a blog, writing posts, and using it to sell affiliates and ads if I were to buy rental properties that create massive amounts of cash flow, once all the work is done and the money comes in passively.
Residual income is the same, but you calculate how much profit you get from the passive income. With the blog you are writing, there are costs such as hosting, plugins, a theme, and even a mastermind group.