Conventional lug nuts / bolts will have six flat sides designed to interface with a traditional socket.
Splined lug nuts / bolts are able to be identified by grooves running down the outer length of the lug nuts / bolts that are removed with the installation and removal tool, or 'lug key'.
In some instances, your vehicle may have a wheel lock which will also have it's own separate lug key. This is usually easily identifiable if one lug nut / bolt on each wheel is substantially different from the others.