Although these two are really different as Anniversary Anyway focuses more on the pleasing side of the teenager's life and on the other hand Our Nineteen gives equal importance to all the sides of life of different teens-Happy, Painful, Beautiful, Memorable, Fun and treasurable moments of life.
Anniversary Anyway have episodes of less duration than Our Nineteen. But the thing that have in common is how sweet the development of relationships are in highschool.In short,Romance is the thing that makes them similar- just sweet and delightful :)

These two series have the same concept-senior year in highschool but are different in their own ways.
What they share is the portrayal of common problems that teens have to face while struggling hard to enter into the adult society
The shows depict what all the teens have to face when the adults emphasize the fact that the senior year of the highschool can change your lives for better or worse.....
These two shows just shows the beautiful,sweet and difficult journey of teens while finding their dreams, maintaining their social life,friendships and learning how to be themselves !!

Even the FL in Our Nineteen has acted in A teen 2!
You might get to see a new side of her !! She is really different there ^^

They are quite similar since both gives the same vibes
Both shows focus on the lives of teens,their problems ,friendships,relationships and their struggles with dreams.

It gives off the same feeling as Someday or oneday because one Female lead character seems bright and the other is little bit gloomy.If I explain more then I might give spoilers to you, so I'll stop here it's just that Female leads are pretty similar and the only difference is this one is a time travel and focuses more on that(Someday or One Day focuses on other things too but Switched is all about learning how to embrace yourselves and the consequences of body switch) but both shows low self-esteem part very well.Somehow both shows gives off the vibes about the inner beauty and how personality makes a person good not it's face/appearance.Although Switched is based on how people's appearances makes them treated differently whereas for Someday or One Day shows how someone's personality makes a difference!

They have a few things in common-
1)The setups for both the dramas is the school life
2)Both of these dramas focus on the eighteen year old kids worrying about their future,
dreams and love problems.
3)The main focus of these two drama shows are the school's strong friendships.
but,
A-teen explores the three points mentioned above in more depth than like. Like focuses more on the content creater part and the fun associated with this activity, also the bickering in love triangle and on the other hand A- teen has a different concept and focuses more on friendship and relationships.