1.) they are the same, but using "zij" is emphasising more. The question "who is the teacher ?" should be answered with "zij is de lerares." , not with "ze is de lerare." 2.) same answer as1 This is a topicthat most native Dutch speaker can not answer clearly, including myself :-)

Ze: unstressed 'she' and 'they (people, things)' Zij: stressed 'she' and 'they (people)' Je: unstressed 'you', also used for unstressed possessive 'your (jou,jouw)' Jij: stressed 'you' (YOU did it) Same principle for we/wij