The feature which best differentiates pressure groups from political parties is that they do not

The feature that best differentiates pressure groups from political parties is that pressure groups do not seek to nominate ministers. While both pressure groups and political parties seek to influence public opinion and policy-making, political parties are structured to nominate candidates for political office and eventually gain political power through elections. Pressure groups, on the other hand, do not aim to directly take political power, but rather to influence those in power by lobbying and advocating for specific policies or interests. Additionally, while political parties usually have permanent organizations and hierarchies, pressure groups may be more loosely organized and focused on a specific issue or cause. Therefore, the correct option is "nominate ministers".