What is difference between Rate Limit Exceeded & Calendar usage limits exceeded

[monawwar29]

I have a service that makes multiple calls to Google Calendar API (list and insert). I am getting "googleapi: Error 403: Calendar usage limits exceeded., quotaExceeded" error after certain period of time.

But when I try to test the same API by manually calling it inside a for loop, it returns "googleapi: Error 403: Rate Limit Exceeded, rateLimitExceeded".

I need to know what are the differences between them?

Thanks!

[nandini3]

In order to prevent spamming, Google has set some usage limits for the calendar. The limits are set above the normal activity level of typical calendar users. If the limits are exceeded, then the calendar automatically goes to read-only mode. The read-only mode does not allow the user to create or edit events.