Experian, Equifax and TransUnion (who we use to provide your score and report in Credit Club) all get information from different sources.

Some lenders will report to all three credit reference agencies, some will only report to one or two. So given the information is different, the scores will be different.

However, the other big factor is that the credit score that each credit reference agency works out is its own view on how the information they have on your credit report might be seen by lenders, and represents this as a credit score. Each credit reference agency has its own methodology to work this out, so your credit score will differ.