@ryan_corris included a picture in his that shows the drop down for Text Match. If you select Close Enough, there is an checkmark option for Spelling Only (ignore case). This is the option you will want to use.
As for the Levenshtein Distance, the higher the number, the more characters that can be wrong and still count it as a correct answer. For your example, a Levenschtein Distance value of 1 means:
sixe(300,200,P3D);
would be counted as corrected because there is only a single character difference between the provided answer and the correct answer. This can be useful in some situations. You can set it to 0 and turn on the option to focus on spelling only so that it requires the correct answer (no mistakes), but allows for upper and lower case.