Yep, there's a lot more to it than it looks. You can have a nice set, and the best of cutters, but if you don't know what to do with them, they're just door stops.
Key blanks aren't the same either. A lot of them look the same, but they're not.
The letters don't tell you the groves. They are marked by manufacturer.
B is the most common. Briggs and Stratton (the lawn mower people) was/is the biggest manufacture of keys for Chrysler, GM and Ford. They still are. They would sublet the work out when they backed up. Most of that went to American Lock, some went to Yale, Curtis and Illco. That's what the letters on the keys mean.
When you buy keys from me, they come from Briggs and Stratton. I have to buy a min of 10K at a time, but they're ran thru the original dies that were used back in the day.
I generally sell things with the newer blanks to make it easier, cheaper for everyone involved. That means I have to rework some of the cylinders to allow for that.