Within the Client list I can see a 'Date last edited' and in the Review module there is a 'Date last reviewed'. Aren't these the same dates?

These dates are not the same.

The 'Date last edited' will show the last date someone updated that client record, such as amended a value, or added a different income i.e. created or changed a record.

The 'Date last reviewed' which you see when in the Review module, refers to the last time that someone clicked on 'Plan overview' and EVPro then build the results for the client.