I have already configured a leadscore call using rest API.Actually, I want to check whether a particular lead score change activity happened via API call or via campaigns?
You would have to run a test record and check the lead's activity log.
Are you saying that the Score was updated from 5 to 10 because you pushed a value via API?
Yes. I have updating score in two ways. one in marketo smart campaigns, another one way is Rest API call from my application. is it possible to differentiate the lead score source?
I am pretty sure the only way you will be able to see this is from within an individual record. The far right column will tell you what campaign was associated with any kind of change, and in this case it would show the API source.