What is the difference between tiled and dynamic services?

A tiled service contains cached tiles, which render the map in small tile images. This allows the map to perform much faster when panning and zooming, compared to a dynamic service. Dynamic is considered an "older" way of displaying web maps, where each feature is called from the source data and drawn separately for every pan and zoom. Tiled base maps are cached from global scale to 1:9,000.