The tools provided by TB are not absolute. TB helps by giving guidelines and suggestions to help steer you in the right direction. The scores should not be taken too literally or as an absolute answer.
In regards to the score analysis change, you are not really comparing apples to apples. There is some overlap but they are very different tools, in my view.
Keyword Explorer is much more narrowly focused in doing preliminary analysis. SEO Explorer is broader evaluating the entirety of title and descriptions you are writing which consist of far more words than key phrases. Keep in mind, that SEO Studio will not teach you to write in enticing, interesting sentences and in a readable, easy to understand manner which matters in real world results.