Markers added directly to map: depending on the scale they can hide each other.

Markers added to map through spreader: if several markers overlap they are displayed next to each other.

Also: check out the labels!

Markers added to map through collator: out of several overlapping markers, the one with the highest z-index is displayed

Both spreader and collator used here: orange markers are collated while teal markers are spread.

Sample markers

Marker, polyline, and polygon in China