Stairends are finishing boards with edge moldings that are on open stair treads.
Wall ends are finishing boars with edge molding placed on treads against a wall. The come in 4, 5 or 6 inch width to match the post sizes.
Treads are complete covering for the floor tread in one piece with edge moldings
Kick board are panels beside the stairs on the inside or outside. They can also cover the expansion joint between floors.
Side trim covers expansion joints or the side of the bottom plate.