Designing thinking is a process that aims to radically change how you solve a problem by diversifying the design team and fully understanding a specific user.

Empathize with your users
Define the users’ needs, the problem, and your insights
Ideate by challenging assumptions
Prototype with basic solutions
Test those solutions

Lean startup approaches product improvement and overall production improvement by creating minimal viable products and letting the customer determine value.

Lean startup elevates the goals of waste elimination, efficient production to quickly validate business ideas and incorporate continuous improvement. Essentially, you identify the big picture associated with each progress phase and using the continuous feedback loop to better engage end users.

Agile is both a methodology for making and scaling your solution with speedy, incremental releases.

Works gets completed in short iterations, known as sprints.
Teams are often self-organized, cross-functional, and based on equality.
Teams are highly communicative, often with daily meetings sometimes known as scrums.
Frequent releases of new features or functions.