Though women were considered inferior in romantic, the female protagonists play a pivotal role in the plot. Both plays depict the expectations society places on these women. Manders expects Regina to help her father whereas Arnolphe expects Agnes to marry him. In both plays, the women don't quite live up to the expectations of the men (Manders and Arnolphe). Both Regina's and Agnes' actions help to move the actions of the plays bringing them to their climax.
In the beginning, Regina is portrayed as a servant and then as the plot develops, we come to know that she was living as a servant in her own home. Arnolphe being Agnes' guardian tries to force her to forget her love for Horace and marry him. However, towards the end of the play, Agnes' real father appears who was Chrysalde's (Arnolphe's friend) neighbour and co-incidentally he had agreed for the marriage between Agnes and Horace long ago without even asking them.
Regina is portrayed as maidservant to Mrs. Alving. Everyone including Regina believes that she is the daughter of Jacob Engstrand and Late Joanna (Mrs.Alving's former maid). But, actually she is the daughter of Late Mr. Alving and Late Joanna which she only comes to know towards the end of the play. Though she is disrespectful to her father, she is full of respect to the pastor, Mr. Manders and Mrs. Alving too. She does return some kind of affection to Oswald but keeping in mind not to step out of the bounds as to what is proper and what is not.
Agnes has been portrayed as being very naive, innocent and totally unaware of the world. She is moulded by Arnolphe from the age of four with the help of nuns to be what she is at present so that Arnolphe can marry her and avoiding the risk of becoming a cuckold. But the climax comes when he actually becomes a cuckold even after taking so many precautions as to not to become one and waiting patiently so many years for Agnes to grow up. Agnes comes to know that she was deprived of knowledge and from becoming wise. After this, she was cautious of what she was doing, how and where. Fortunately, at the end of the play Agnes gets to marry the person of her choice.
Both Manders and Arnolphe try to get Regina and Agnes to adhere to the rules and norms of the society. Manders does this through the strength of his verbal skills while Arnolphe tries to conquer this through the help of Maxims.
Both Regina and Agnes hate their guardians from the beginning of the play. Regina thinks of herself superior from her father and doesn't give him the respect which he deserves "I am not going to have any one find you here; so now you know, and you can go"  and she doesn't know about his favour towards her and her mother till the end of the play, whereas Manders wants Regina to stand by her father "But a daughter's duty, my good child"  . Agnes on the other hand, does not hate her guardian from the very beginning of the play but as the play proceeds, she comes to know about the intensions of her guardian and hates him.
Both Regina and Agnes leave their guardians towards the end of the plays. Regina leaves Mrs.Alving saying "I know one house at any rate where I shall feel at home"  and Agnes leaves Arnolphe when she is about to get married to Horace.
Both Regina and Agnes fall in love with someone whom their caretakers wouldn't agree as their partners. Regina falls in love with Oswald (her step-brother) and Agnes falls in love with Horace, Arnolphe's good friend.
"Oswald. Regina is going away with me, Mr. Manders.
Manders. Going away! With you!
Oswald. Yes, as my wife - if she insists on that.
Manders. But, good heavens---------!
Regina. It is not my fault, Mr. Manders." 
Manders doesn't expect her to fall in love with Oswald as he knows about their actual relationship "Manders. But, good heavens---------!" 
"Agnes. He's better at those things than you, for all your schemes: He made me fall in love, and with the greatest ease."  Arnolphe too did not expect Agnes to fall in love with Horace as Horace was his good friend and he thought that Agnes knew nothing about love. He thought she was naive "You wicked girl! You know it's wrong to love him." 
While Regina does not respect her father in the beginning of the play "Don't clump about like that, stupid! The young master is lying asleep upstairs."  Agnes respects her assumed father (Arnolphe) in the beginning and tells him everything "Oh, goodness, please don't bet, because you'll lose your stake!"  Both of them come to know truth about their guardians as we proceed towards the end of the plays and the truth is exactly opposite of the view that they held in the beginning of the plays.
Agnes thinks of Arnolphe as her father but Arnolphe doesn't want her to think in that way "I planned to marry you myself"  . Whereas Regina doesn't want to think of Engstrand as her father while Engstrand wants her to think of him as one "He's the chap to tell you what a child owes to its father. For I am your father, anyway, you know. I can prove it by the register." 
When Manders asks Regina to help her father out, she denies it giving the reason that "But I don't know whether Mrs. Alving could do without me - most of all just now, when we have the new orphanage too see about."  - But Manders expected Regina to go with her father and help him out as he is in most need of her.
Whereas, Agnes wants to leave her guardian whom she was indebted to, Arnolphe expected her to be with him when he needed her for his marriage.
If we compare both the plays where The Ghosts was written in 1881 while The School for Wives was written in 1700, both the plays have some kind of similarities and dissimilarities. After reading both the books, I feel that there is a strong portrayal of society, yet it is portrayed in their own individual ways. Some aspects of the society have been highlighted in both the books. One of the main being marriage, role of men and women, law and order, the idea of free love and the way the servants are treated. During the periods when these books were written, men only used to think about themselves and cared mostly about the money. Women though were very sharp minded and intelligent, were quite submissive in nature.
By keeping all of the above points in mind, we can easily come to a conclusion that despite the fact that Regina and Agnes are two characters from two different plays, still they have quite a few similarities as well as contrasts. Where Regina seems to be pretty intelligent and aware of her surroundings, Agnes seems to be tremendously naive yet a bit conscious of her surroundings through the help of her lover Horace. While Regina hates her father in the beginning of the play and realises that her hatred towards him was wrong, Agnes likes her assumed father (Arnolphe) in the beginning and realises that her likeness towards him was not apposite.
I feel that without an important role of women in a play, a play can neither be complete nor interesting. Women are the ones who add the suspense, confusion and the eagerness which leads the reader to read the entire play and enjoy it without getting bored. Women are the ones who sometimes help us in understanding the real character of a person in the play. Therefore, according to me, if women do not play a relatively important role in the play, the play won't be as interesting to read as it could have been and many aspects of the society and the characters would remain undisclosed.