What is consistency of design?
Consistency in design is about making elements uniform — having them look and behave the same way. We often hear designers talk about consistent navigation, consistent page layouts, or consistent control elements. In each case, the designer is looking for a way to leverage the usability by creating uniformity.
What is a design Styleguide?
A style guide is a set of standards for the writing and design of documents and materials. A design style guide usually addresses logo usage, fonts, colors, and sometimes page layouts. The use of a design style guide provides uniformity in the application of graphic elements and the formatting of materials.