Rachel Dolezal

I'm still confused about the incident concerning Rachel Dolezal.  Rachel Dolezal is a white woman who tried to act and look Black by changing her hair and attempting to make her skin darker.  Why does she want to be Black?  Because of racism and stereotypes, there is differences in each race.  But what makes Rachel Dolezal wish to be Black instead of white?  I understand the idea of wanting to be the opposite sex because of the defined physical differences, but why does she want to be black?  What are the true differences between being black and white?