Change output to show the difference between fixture data and fields

This modificación makes easy to know why the fixtures fails when the amount of fields in the data is different form the amount of fields in the schema used in the fixture.
In my case, a fixture with model import and static records data gives error, but doesn't say which fields is to blame. The import model gets a new field but the data stills with old amount of fields, and the error is thrown.

Maybe some optimization could be maded in the comparation.