Two independent choices. Layout is where the units go: a heart, a house, a plain grid. Mark is what one unit looks like: a dot, or a pictogram. They compose, so a crowd of people can be arranged into a heart and the same crowd can walk into a house without either choice knowing about the other. Pick one of each.
1 glyph = 10 volunteers. Each glyph is one drawn path, filled in its own colour, so the crowd stays this size without a per-icon image or a recolour filter.