login are both calls that can be made to the IDSync API to identify a user, but they have different use cases.
identify call is made automatically each time one of the mParticle SDKs is initialized. For example, any time a user opens a new page in your app that initializes an SDK, then the SDK will attempt to identify that user using any existing cookies or available user identifiers. The
identify call is used to identify either known or unknown users.
login call should be triggered by your app whenever a user logs into your app by providing a Login ID (a member of a subset of user identifiers used to identify a single, known user). The
login call is used to identify known users only.
For general information about the IDSync API, refer to our Identity API documentation.
Instructions on how to call the IDSync API using one of the platform SDKs can be found in the developer documentation.