amateur: Like in sports, amateur porn features individuals who are not professional porn stars. It features ordinary individuals partaking in every day sexual acts. Girl/boy next door, wives/husbands, girlfriends/boyfriends. Sometimes real amateurs but quite often professional models just pretending.
cuckold: Cuckold porn is a genre depicting a man whose wife cheat on him by having a sexual relationship with another man. This is often happening right in front of the husband. This fantasy involves both a domination (from the wife and her lover on the husband) and a voyeurism dimentions.