i am confused .how does one draw the line if any between the national parties and local parties

i read that                                                                                         local party organisations select candidates, discuss policy, and canvas the voters in national, local, and European elections 

contrast this with the statement below

annual natioanl party conferances  are carefully managed and well publicised events

also

Which party can have a significant effect on the Parliamentary leadership?










[ A ]



 General party



[ B ]



 National party



[ C ]



 Local party





thanks