Jack -- Here's the key. A WSM is designed to run as a low temp smoker. In contrast, a kettle is designed to run at much higher temps as a grill. The food in a WSM is two feet from the fire. Only 4-6 inches in a kettle.
So, as others have mentioned above, the WSM is designed to run at 250F (more or less) when using some form of the stock Minion method. Which is having a big pile of unlit charcoal and then adding a limited number of lit coals to the unlit pile. The fire advances slowly through the unlit pile -- pretty much how a snake fire progresses in a kettle. To keep your kettle at 250F, you have to work harder at it and do some extra tricks -- like the snake.
Because of the smoker (not grill) design of the WSM, you'd only need to use a snake (like you use in a grill/kettle) if you want extra low temps under 200F. You'd only use those temps for specialty cooks like bacon, jerky, smoking cheese, etc. Outside of those specialty cooks, us MSM-ers will usually Minion and rarely snake.
The fundamental variable in your WSM cook is how many charocals you light up at the beginning and add to the unlit pile. On a hot day, not using water, no wind and a modest amount of food, you might start with only 8-10 lit coals. On a cold windy day with a full cooker and a full water pan, you might start with 3/4 of a big chimney lit.
After the fire gets going, you can fine tune the WSM temp much easier by playing with the multiple vents. The vent adjustments on a kettle are not as precise.
Bottom line, a kettle is a fine grill that can be a meh smoker if you jerry rig it. A WSM is a fine low temp smoker that is designed to run at 250F without any special methods.
Welcome.