"we use a lot of data to inform our decisions, but we also rely very heavily on iteration, research, testing, intuition, human empathy. It's both art and science....data analytics will never be a substitute for design intuition. Data can help you make a good design great, but it will never made a bad design good." - Margaret Gould Stewart

Source: The Lean Agency | UX matters

Instead of thinking how to cut cost or minimize spending, lean UX focus on when and how money is spent!!

Business Goals + User Goals + User Interface + Technology = User Experience
Five Planes of UX = Strategy, Scope, Structure, Skeleton, & Surface (from abstract to concrete)

Wireframe:

A wireframe is a low-fidelity representation of a product’s design.
The visual characteristics of a wireframe are very limited. Usually designers just use boxes, lines, and a grayscale color palette (to represent different levels of visual hierarchy in the design).

Interactive Wireframe (figure)
Sometimes designers like to increase the fidelity of their work a bit to stress the importance of certain parts of the UI, as well as to present and quickly test the soundness of interactions between elements. A very popular way of doing that quickly is the creation of an interactive wireframe, also known as a clickable wireframe.

Prototype:

A prototype is a mid- to high-fidelity representation of the final user interface.
The goal of a prototype is straightforward: Simulate the interaction between the user and the interface.

Visual Characteristics of a Prototype When it comes to aesthetics, a prototype may closely resemble the final version of the product.

Basically, a prototype looks like the final product (figure), but it just doesn’t have the nuts-and-bolts yet (i.e. HTML, CSS, JS, server-side programming, databases, etc.).

Source: Lessons from the "Seductive Interaction Design" Book

Source: Infrographic