main goals :
Site Reliability Engineering (SRE), The main goals are to create scalable and highly reliable software systems. According to Ben Treynor, founder of Google's Site Reliability Team, SRE is "what happens when a software engineer is tasked with what used to be called operations."
It's also been associated with a practice that encompasses automation of manual tasks, continuous integration and continuous delivery.
SREs, being developers themselves, will naturally bring solutions that help remove the barriers between development teams and operations teams.
difference devops with sre:
SRE and DevOps share the same foundational principles. SRE is viewed by many (as cited in the Google SRE book) as a "specific implementation of DevOps with some idiosyncratic extensions."