Hi Huma, Software Testing Engineer and Quality Assurance Engineer both have their own methods and ways of checking whether a software application is upto the standards and can be passed for release or not. A Software Tester explores the ways to check how an application works and find the possible defects. Various methods and testing methodologies are used by testers to test the product, locate bugs and check if they are fixed. Testing enables customers with the possibility to see if the developed product meets their expectations on its design, compatibility, functioning, etc. Tester's main focus is to test the application and find all the possible bugs which could crash the application.
While on the other hand, a QA Engineer follows a set of methods and activities designed to ensure that the software application is as per standards or SRS and corresponds to all the specifications. It is a planned strategy of the testing process evaluation aimed at the quality product yield. QA Engineer works out ways to prevent possible bugs in the process of software development. They also deals with the management stuff like methods and techniques of development, project analysis, checklists, etc. QA goes through the whole product life cycle (SDLC) and heads the process of software maintenance. Their main focus is Quality Control and to make sure requirements are met properly.
Hope this helps!
Check out this Manual Software testing course and learn from the expert.