Parties envisage the type of society that they wish to see, devise policies to create that society based on evidence and argue the case even when unpopular.
Parties sacrifice aspects of their vision to create a more popular programme ditching unpopular policies.
Parties reduce their policy programmes to slogans which at least pay lip service to their original vision.
Parties reduce their policy slogans to meaningless platitudes about ‘fairness’ etc.
Parties make up any shit however inaccurate or offensive if they think it will help them win.