Renovation is the process of renewing a building or structure by fixing what's already present and in some cases adding new components.
Renovation tends to be cheaper than remodeling. Depending on the project, it can also be more cost-effective than restoration.
Typically, renovations are done in conjunction with restorations. For example, someone may decide they want to restore their bathrooms. But to make it a bit more modern, they add a shower component to the tub, which would make it a renovation project as well.