How to differentiate candidates who are currently on a career break from the candidates who have never had any professional experience?

You can differentiate the candidates on the basis of the total experience the candidate holds.
 
For example, the intern will have an experience of 0 yrs while the candidates who have a career break will have experience along with the gap period.
 
Please refer to Experience (rchilli.com) How do you calculate the total number of years in experience?

If you have any questions or concerns, please don't hesitate to reach out to us at support@rchilli.com