Surprised I didn't see this asked before but when watching videos about suspension components and installs I've commonly seen people refer to, what I would imagine a spindle, but call it a knuckle. So what is the difference between a spindle and a knuckle or are they both the same?
The knuckle is the part the spindle attaches to. The spindle carries the hub and bearing(s). Generally the spindle is used on non-driven wheels, but there are some where the spindle is hollow and the CV shaft extends through e.g. Some Nissan's. The bearing(s) and hub assembly are still on the spindle, there will be a drive flange that bolts to the hub.
A spindle attached to a knuckle.
A knuckle for a bolt in hub and bearing setup.
The term seems to be used interchangeably though.