I also have a recipe for Arepas from Colombia on my website. Arepas are pretty similar to pupusas, though there is a slight difference between the two!  The main differences are that arepas are made with masarepa, while Pupusas are made with masa harina. Both are cornflours, but masarepa is precooked.  The other major difference is that arepas are stuffed with fillings AFTER cooking, whereas pupusas are filled prior to cooking.