Your credit score is calculated completely on the basis of information present in your credit report. Your credit report is a complete record of all your credit transactions which include your payment history, credit limit, highest balance ever charged and the age of account.
While the exact credit scoring, is the secret of the companies that calculates the credit score, the credit score is calculated using five major chain of information which are credit utilization, payment history, Inquiries is, mix of credit and age of credit. All this information is present on your credit report.
It is possible that your credit file with different credit bureaus might be different. For this reason your credit score may be different across different platforms depending upon what information they have access to and in which credit file from which credit bureau.
Any changes that occur in your credit file will probably result in changes in your credit score as well.