they're both realistic and have a natural paced love/slice of life plot. also, the leads in both dramas are studying at university. the only difference i'd say is that the leads in unrequited love knew each other before in middle school, but apart from that, the dramas have a similar vibe

the characters are in university in put your head on my shoulder, but i found the dramas to be pretty similar despite this.
they both have the male lead and female lead living together facing the hardships of their jobs/school life, and fall in love at a realistic pace despite not really hitting it off at first.
i think the main similarity is that both of these dramas are realistic and actually have a natural pace to them, they're both quite simple and pretty much just follow the main leads' daily lives whether they're at work, university or living together. but, i think that's what makes both of them stand out in the kdrama/cdrama world. it's refreshing to not have any annoying drama tropes and just a natural, realistic slice of life and romance mix.
i would say because this is my first life is more mature than put your head on my shoulder tho, if thats an issue to you.

although the theming is quite different, i noticed some clear similarities between the two as i was watching.
• political corruption
• antagonists neglect the community (contaminated water in tuc, food poisoning in tfp)
which causes a child's illness
• group of skilled people work together to get justice served
• satisfying endings with the antagonists finally getting what they deserve, after constant
failure
• comedy, investigation theme

• cute romance that blossoms through school, university and eventually to adulthood
• starts with female lead's unrequited love to the male lead (male leads' feelings are quite
obvious by the halfway point in both dramas tho)
• second male lead syndrome :( however one difference in a little thing called first love, is
that he actually finds love through the second female lead towards the end
• youth, school and slice of life theme
• slow burner romance

they're both very similar imo, the only difference being the mom at school and the cheerleading

• school corruption (justice is served in both dramas)
• comedy and school genre
• 2nd gen idol actors (baro and lizzy in angry mom, eunji and n in sassy go go)
• character development for most main characters
• enemies to lovers (sang tae and ah ran, yeon du and yeol)
• shows students' mental health and how it deteriorates due to their parents'/teachers'
actions.

both focus on sports and the main couples both go from enemies to lovers. also, it focuses on the university life, as well as the leads' roommates and families. they're both similar in good ways