Actually, the translation for both "Puder" and "Pulver" would be "powder". "Puder" is usually used for cosmetics (baby powder - Babypuder) and also "powdered sugar/confectioners' sugar/icing sugar" is "Puderzucker", while most chemical and pharmaceutical products would be "Pulver" (gun powder = Schießpulver). Please note that it's "der Puder", but "das Pulver".