In George Bernard Shaw's Arms and the Man, Louka the maidservant and Raina the mistress are deliberately contrasted women. Their differences of class, temperament and conduct allow Shaw to satirise social pretension and to show that worth is not determined by birth.
Social class. Raina is the daughter of the wealthy Petkoff family, a well-born young lady raised in comfort and privilege. Louka is a servant in that household, of humble origin. This gulf of class is the foundation of their contrast and of the social comedy Shaw builds upon it.
Ambition. Louka is fiercely ambitious and determined to rise above her station. She refuses to accept that her low birth should confine her and openly aims to marry into the upper class, eventually winning Sergius. Raina, already privileged, has no such need to climb and takes her position for granted.
Honesty and pose. Raina, at least at first, is affected and romantic, cultivating a "noble attitude" and a false ideal of heroism and higher love. Louka, by contrast, is frank, shrewd and clear-sighted; she sees through pretence, including Sergius's, and speaks plain truths that the genteel characters avoid. Shaw uses Louka's realism to expose Raina's posing.
Courage and boldness. Louka is bold, defiant and daring, willing to challenge her social superiors and to pursue Sergius against convention. Raina is more sheltered and conventional, though she too grows bolder and more honest as the play proceeds.
Development and outcome. Both women shed illusions by the close. Raina abandons her romantic pretence and accepts the realistic Bluntschli, while Louka secures Sergius and rises in status. Their parallel yet contrasting fates underline Shaw's point that intelligence, honesty and force of character matter more than rank.
Shaw's satiric purpose. Through the contrast, Shaw ridicules the class snobbery of the Petkoffs and celebrates the spirited, self-made Louka, suggesting that the servant's shrewd realism is in some ways superior to her mistress's inherited refinement.
In conclusion, Louka and Raina differ in class, ambition, honesty and boldness. Raina begins as the affected, privileged romantic and Louka as the frank, ambitious realist, and through their differences Shaw attacks social pretension and affirms that character outweighs birth.