Hi @sagarpundir ,

A system property is any configurable key-value stored in sys_properties that controls behavior; a base property is the Out‑of‑Box definition delivered by ServiceNow that serves as the default “source” value before any customer override.  “System property” is the actual record/value in the instance that code reads via gs.getProperty().

Base property” refers to the Out‑of‑Box (OOB) property value delivered by ServiceNow as part of the base system. 

A system property is a configuration setting stored in the sys_properties table that platform and application code read at runtime

For more detail checkout below article.

System Properties & it's Usage 

Thanks,
Bhimashankar H

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