What is the difference between a pressure group and a political party?

Difference between a pressure group and a political party is as follows:

a) Pressure groups contains those people who have same interest and aspirations and have a common objective or goal to achieve whereas political parties contains those people who come together to win the elections and hold the government

b) Pressure groups are not accountable to the citizens of our society whereas political parties are accountable to them

c) Pressure groups do not have direct power in their hands whereas political parties have directly control over the power