What distinguishes communists from other working class parties?

From the text:

The Communists are distinguished from the other working-class parties by this only:

(1) In the national struggles of the proletarians of the different countries, they point out and bring to the front the common interests of the entire proletariat, independently of all nationality.

(2) In the various stages of development which the struggle of the working class against the bourgeoisie has to pass through, they always and everywhere represent the interests of the movement as a whole.

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The immediate aim of the Communists is the same as that of all other proletarian parties: Formation of the proletariat into a class, overthrow of the bourgeois supremacy, conquest of political power by the proletariat.