For starters both r Japanese BLs.Both have this one guy who is very sure of his feelings and this straight guy who is very flustered at first .both have that office background.even the actors look similar.

Both the ML are bad boys.both r tough guys falling head over heels in love with a sweet girl.while man in love is much more sweeter .miss shampoo does have a lot of jokes one might find vulgar .but both r still hilarious

Both have cute leads and very sweet moments between .I'd u liked one u will definitely like the other

Both r jdramas and r so cute
Both r kinda contract relationship but eventually fall for each other

Both dramas have older FL being chased by young ML.
Both have adorable chemistry between the leads.

Both dramas are set in the 80s/90s.
Both dramas try to portray the past very accurately in the choice of hair ,costume and music.

Both the drama have family and friendship as its core topic.
Both of them have the best leads and the best romance -yichan and Cheong ha in TW
Deok sun and Jung hwan in Reply 1988 .
Ofcourse in TW we do have a happy ending for this romance

MNCS is not a BL.but it has very similar plotline to ABOL.both the ml suffer from insomnia and both can only sleep with the other lead.
Both the ml are kinda cold in the begining but turn out to be very soft

Both are Korean BL.both are based on college .

But blueming is definitely so much better .it's so good .if you haven't watched it yet I really recommend a watch

The similarities :Both of them have a child of the main lead going to the past where the parents are in high school.both the parent characters r bad in studying and they help them with their studies.
Both of the future child ends up falling in love when they're in the past .both r cute and heart warming stories .both the child lead tries to make their parents fall in love with each other .

The differences: in TW the main lead is a guy whereas in idwtbfwu it's a girl lead.
In TW there's two characters that's travelling into the past making their love story a bit easier .since they can still be with each other in the future .
Whereas in idwtbfwu the girl lead falls in love with someone in the past .that makes their love story a bit more complicated .

I finished idwtbfwu and it's a beautiful story . totally recommend it

It's both very fluffy dramas with childish fl.
In both the fl falls in love with the ml first and persues them

They r not similar in storylines.
If extracurricular is occurring in school .dp happens in prison
Both have good characters forced to do bad things bcoz of their circumstances.
Both the dramas r Netflix shorts
Both are really thrilling and will have u on the edge of ur seat .
U will wanna watch both dramas in one sitting as it is so exciting .
If u liked extracurricular for the thrilling experience u will love dp.
Disclaimer : dp has some sensitive scenes regarding bullying in the prison .so please be ready before watching

Both have the sweetest stories ever
Both have great acting by the leads
Both r well cast and have great OST