What is the difference in the use of propaganda and the use of bias within political parties?

propaganda-information, especially of a biased or misleading nature, used to promote or publicize a particular political cause or point of view.

bias-prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair.

i think its the outcome of people's preferences.

the triple alliance. germany and austria-hungary were already allies by 1879 when, worried about a threat from russia, they formed the dual alliance. italy joined the group in 1882. there was a concern about a possible attack from france and the alliance needed powerful friends to defend it.