The data supplied by our data providers determines the accuracy of features on a map, and the spatial accuracy of occurrence locations varies greatly. Some records will only state that a species was observed in Australia while others will be accurate to within less than 5m on the ground. The Darwin Core term coordinateUncertaintyInMeters, where available, can help you view spatial accuracy. You can examine many of the Darwin Core terms for mapped occurrence records using the Spatial Portal’s legend
Named locations are generally accurate to within 100m but this will depend on the context, eg the centre of a town in 1950 will probably not be the same as it is today.