They are both body swapping rom-coms. But in PPO the female lead switches bodies with the male lead's niece.

Both are love stories about a top star and a regular girl. Also in both stories the male lead uses another girl to try to make his childhood love upset. But in Jai Rao the female lead is his childhood love.

Both are about two strangers having a one night stand and accidentally getting pregnant.

Its the same female lead in both series and she sees ghosts in both series.

Both stories are older woman / younger man romances.
In Biscuit Teacher Star Candy it's a student / teacher relationship and in Ruk Sutrit it's a teachers assistant and a boy she tutors who fall in love. Also in both the male lead starts out as immature rich brat only to grow and change because of the female lead.