Is Sentinel a SOAR or SIEM?

Could you please clarify for me the distinction between SOAR and SIEM, and how Sentinel fits into either of those categories? Is Sentinel designed to automate the incident response process, functioning more as a SOAR tool, or does it primarily focus on monitoring and analyzing security events, making it a SIEM solution? I'm interested in understanding the primary purpose and capabilities of Sentinel and how it might be used within a security operations environment.