Complex sentence: Pictograph has a rather different meaning in the field of prehistoric art, including recent art by traditional societies and then means art painted on rock surfaces, as opposed to petroglyphs; the latter are carved or incised.
Split into simpler sentences: Pictograph has a rather different meaning in the field of prehistoric art, including recent art by traditional societies. Here it means art painted on rock surfaces, as opposed to petroglyphs that are carved or incised.