People refer to the two as "Third World/South" and "First World/North" because the Global North is more affluent and developed, whereas the Global South is less developed and often poorer.
Orang-orang menggunakan istilah "Dunia Ketiga/Selatan" dan "Dunia Pertama/Utara" karena Utara Global lebih kaya dan maju, sedangkan Selatan Global belum maju dan cenderung miskin.