Are bike forks universal?
Will any fork fit my bike? No. When replacing forks it’s key to know your head tube diameter as you will need to pick a fork with a matching steerer tube.
What’s the difference between threaded and threadless forks?
The threadless fork is easier to stock since it can be fewer sizes, it can be cut to fit the bike. Whereas the threaded fork has to be cut to the correct size, or rather manufactured to that size. Thus this makes it cheaper to stock the threadless forks.