Thread that is stack wound (thread lies one thread right next to the thread on the last round), should come off the spool from the side, so should go on the spindle of the machine. Thread should come off the back of the spool.
Thread that is cross wound (thread crosses over all the other threads on each round), should come off the spool from the top. Some machines have a sideways spool holder for those. Otherwise, they need a thread stand so that the thread can come off the top of the spool. I have already set the cone on the floor. Cats love that.