Actually, the term "Hate" is used in Asian games and is analogous to western "Threat". Threat and Aggro are a bit different. Threat is a numerical value assigned to every party member, while aggro is a flag assigned to the current target. The most important difference is that aggro is not simply assigned to the target with the highest threat - it also needs to surpass the threat level of the current target but a certain percentage. That allows tanks to keep the aggro even if the threat is on par with the DPS teammates.