I do not mind answering legitimate questions such as the one on deduction etc., but here the answers can be found in ANY dictionary. I get the feeling I'm being bamboozled into doing your homework.
TheSiavash: Coming as it does three years after your question, this will probably be of no help to you (since you have probably given up on this site), but it may be to others. A current Google check of 'difference banister baluster' (without quotes) gives a number of more or less consistent sets of definitions, which boil down to:
handrail is an inclined molding providing support for one