The similar points between shows are highliting the married life of female and male leads couple.
Female leads who were a devoted wife but unlucky in their married life.
Female leads who gave up their career in order to raise their childs and being a loyal housewife.
Second chance who let the female leads to practice their preferred career (journalist/doctor) after struggling with male leads.
Female lead who met in their journeys the second male leads who seem interested in their characters.

Both shows include a couple who are doctors and working in the same hospital.
The female lead who was a housewife becoming a trainee doctor after being married for a great time.
Problems in relation between the couple (divorce/infidelity) but portrayed in funny way.
Male lead who is the main cause being the trouble in the married life.
Second female lead doctor who is ruining the relation of couple.
Medical team supporting characters and similar hospital settings vibes.
The same nasty actress playing the role of male lead's mother.
Female lead who gets entangled with the second male lead doctor interested in her character.

Both of shows include one of parents who reenter the high school/college life after many years being married and raising their childs.

The main common points the couples are about to be divorced and parents (female in 20 again and male in 18 again) are in the same college/school of their childs.

Female leads are trying their luck to study the major she wanted in 20 again and the job she dreamed before marriage in 18 again.

Both of female leads having same character of innocence and being criticized by their surroundings for being older than their colleagues.

Shows of second chance in life and love theme but fantasy genre in 18 again where the male lead return to his old young self to rectify all his mistakes.

Both of these dramas are including the same male lead who is showing the same affection and performance.
It is based on the opposite concept for the male lead of being the younger in the old drama and the old in the newest one.
But though it is been 21 years difference between the both, where they embody the same characters of male lead in my opinion with same romantic genre story.
What is the common I think is that the relationship between the leads is not lasting for long time at the end of story and painstinkly resisting to not be separated.

Both are about male leads who lost their ex-girlfriends in an car accident/suicide and seeking revenge from the side of female leads by thinking they are the main cause of the deacesed.

Female leads are rich/celebrity.

The male leads intend to approach the female leads to work as a bodyguards to find the truth behind the death.

Male leads teach female leads how to defense themselves from any enemies to earn their trust but instead their relationship develop in romantic way.

Both of shows seem having different plots but from watching the trailer of the glory some common points I think there are:
-They include the psychological and trauma issues of leads from school bullying.
-Dark side hidden in the past of leads.
-Both male leads come from a rich family and are liked by everyone.
-Great chemistry between leads as partners in drama.
-Childhood trauma side happening in school/college: The female leads in the glory and ADSIG was facing school bullying whereas
the male lead in at a distance spring is green was abused by his horrible and evil figure parents.
It is most revenge type for the glory but romantic for ADSIG.

The similar points between two shows are:
-Hard working male lead to achieve his goal in sports domain:
high jump/running marathon
-Coach-trainee relationship
-Supporting female lead, is training the male lead and following all his progress
-Male lead facing hardships and problems with his height comparing to his pears and being bullied
-Male lead insisting to challenge all his difficult circumstances to prove himself
-Older female-younger male with great age difference

Both shows sound so different but the common points are:
-Both male lead grew up in a poor and rude environment
-Male leads have a dream to reach: being a pediatrician/marathon runner
-Challenging all circumstances to attain their goal
-Nice female leads supporting for the dream of male leads
-Male leads though the opposition of all their surroundings, they excel in their field medical/running
-Fathers of male leads are discouraging characters
-Have the male and his brother relation focusing

It sounds so different in plots but common points are between the two shows:
-Female leads are bullied in university
-Female lead trapped in love triangle
-First male lead is so jealous from the relation of female lead with other male lead
-Nice male leads but hide their real personality
-Female colleagues are jealous from the female lead and pretend to be nice to her
-Leads in their twenties
-Male lead tend to be lonely having few friends
-Male lead is popular in the university
-Male lead always caring about the female lead
-Male lead coming from a rich background
-Female leads are confused towards the male lead

Both shows involves mainly female leads who play bodyguards for the rich male leads who is surrounded by enemies.
Poor female lead, hired as his employee having skills in fighting.
SWDBS is more comedic with a fantasy female lead who inherit a special power from her mother generations.

Both include leads who are facing hardships and psychological issues.
It happens in college frame with rich and popular male leads.
Male leads have family problems, they pretend to be okay but are traumatized from a long time.
Male leads have a main problems with their brothers who are jealous of them and family focusing for brothers more than the male leads.
Female leads were bullied in college but is more intense in mars.
Mars is more deeply sad than at a distance, spring is green which is simple to watch.

Both shows about female leads who were once successful in their field of work but suddenly a psychological state they fall in make them feel uneasy and in perpetual depression.
The female leads have problems with their husbands who are leaning to their first love.
The female leads were pregnant and had miscarriage which make difficult form them to return being hardworking.
Both dramas have in common mystery and ambiguous sides in the sequence of events.