Contact and non-contact forces
Gravity and magnetism act at a distance; friction and pushing a trolley need surfaces actually touching.
A worked example
A magnet tugs a paper clip across the table before the two ever meet, so magnetism acts at a distance. A rolling ball slows only because it rubs on the floor.
The mistake people actually make
Only a few metals are attracted to a magnet, mainly iron, steel, nickel and cobalt. Aluminium and copper are metals but a magnet ignores them.