Software engineering is the systematic application of engineering approaches to the development of software.[1][2][3] Software engineering is a branch of computing science
Software engineering is the process of analyzing user needs and designing, constructing, and testing end user applications that will satisfy these needs through the use of software programming languages. It is the application of engineering principles to software development. In contrast to simple programming, software engineering is used for larger and more complex software systems, which are used as critical systems for businesses and organizations.
Source: https://www.techopedia.com/definition/13296/software-engineering
The Software Development Life Cycle in systems engineering, information systems and software engineering, is the process of creating or altering systems, and the models and methodologies that people use to develop these systems. The concept generally refers to computer or information systems.
In software engineering the SDLC concept underpins many kinds of software development methodologies. These methodologies form the framework for planning and controlling the creation of an information system[1]: the software development process.
Source: https://en.wikibooks.org/wiki/Introduction_to_Software_Engineering/Process/Life_Cycle