similarities:
1. both of these dramas take place in the past, around the same time give or take a few years. Love Rain takes place earlier in time (1970s) and Youth of May in 1980.
2. the love between the leads is deep, unexpected and life altering.
3. separation of the leads due difficult circumstances. the lovers never forgot each other till the present day, even though they have been separated for decades.
4. tragic ending - unfulfilled love.