et al. is short for et alia (and others). It is generally used in English for lists of people.. It is generally used in English when referring to people. “The study by Smith et al. reported that …”
etc. is short for et cetera (and others [other similar things]). It is generally used in English when there are other things that could be listed but readers should get the idea by now. The car collection had Porsches, Camaros, Yugos, etc.