Dia-Compe sidepull caliper brake. Brake bolt is rolled: the bolt is nominal size at the brake arch, then necks down to be slightly undersize just before the threads start. Rolling raises the threads back up to nominal diameter. At the very end of the thread there is a circular, non-spiral ridge all the way around the bolt, a sort of sterile thread, which is apparently a typical relic of rolling. This is a little hard to see in the picture but is verifiable by looking around the bolt. Current-production Shimanos and the 1980s Dia-Compes I looked at all seem to be like this.

Suntour Superbe sidepull brake, with drop bolt. Brake bolt has cut threads. The shaft is the same diameter all the way; rolling would raise the threads, cutting leaves the thread apexes at the nominal diameter. At the end of the threads, there is not a sterile thread. Rather, the valley of the last thread gets gradually shallower until it disappears (this may be a little hard to see in the picture). This is possibly due to a cutting tool gradually withdrawing from the work. I think this is a sign that the threads were cut on a lathe rather than threaded down with a die until a stop.