Русско-англо-русский юридический словарь

To haggle is to bargain with more effort. The verb haggle also has a negative connotation in Western culture, sometimes. It defines when someone is bargaining to the point of annoying the other person. (italki)

Haggling and bargaining are both used to talk about something, especially prices, to reach an agreement, with the only difference that the former is a bit harsher in which there is some sort of anger, noise, disagreement or heated conversation, whereas the latter is softer, in which parties normally remain composed. (StackExchange)