Difference between WMTS and WMS?
The WMS standard allows the client to request an arbitrary region. If the client wants tiles, it can makes its requests in a tiled pattern, but the server has no way to know that's what's happening and if the server stores the map as tiles of its own, it has no way to let the client know what the tile arrangement is.
https://gis.stackexchange.com/questions/53011/difference-between-wmts-and-wms