What is the difference between MontBlanc Rollerball Refill F-Point (Fine Point) and M-Point (Medium Point)?

Fine point and Medium point refers to the boldness of the ink or the visibility of the ink when you are writing. Fine point is usually .5mm and medium point is usually .7 or 1.0mm, Words written in medium will appear more bold and richer, as fine point will appear very skinny. This is the case for all pens, one of my favorite pens to use is the paper-mate profile which has a bold point that has a point size of 1.4mm.