There is really only one type of chalk line as they are all designed to do the same fundamental task, though some chalk lines may have additional features which give them advantages over others. Below is a list of some of the more common features.
Belt clip
Not all chalk lines have these, but a belt clip is a simple curved piece of metal typically attached to the chalk line box via a screw. The belt clip allows you to hook the chalk line onto your belt so you can quickly access the tool when working.
Geared crank
Chalk lines with a geared crank (and a gear ratio higher than 1:1) allow you to wind the string in faster, meaning you expend less time and effort. For more information on geared cranks and gear ratio see the page entitled:What is a chalk line’s gear ratio?
Chalk window
There are models of chalk line that have the additional feature of a transparent window in the side of their box so that you can see, at a glance, exactly how much chalk powder you have left. This reduces the chances of running out of chalk half way through a job.
Plumb-bob tapered end
Many chalk lines have a tapered end so that you can use them as a plumb-bob to mark accurate vertical guidelines, check for plumb, as well as transfer points from floor to ceiling. The tapered point on the bottom of the chalk line promotes accuracy and you may find that chalk lines without this additional feature are difficult to use accurately as a plumb bob.
Plumb-bobs
A plumb-bob is a tool used to create a vertically straight (plumb) reference line. It consists of a piece of string with a weight attached at one end. The string is attached to an object and the weight is suspended below. Because gravity will always pull the weight directly downwards, your string will always be in a vertically straight line. Learn more about Plumb Bobs