Ticking is generally the top end and usually a lifter. Knocking is sometimes the bottom end and is due to a bad main or rod bearing. That kind of knocking is a serious SERIUOS problem. A sticky lifter is minor and can usually be corrected with additives to thin the oil or detergents to flush out the clogged lifter.

A solenoid knock will sound like marbles being thrown around in the front of the valve cover. If you feel the cover you can actually feel the knocking under it. That is also a rather serious problem. You will also notice you are down on power if a solenoid is failing.