both are criminal detective dramas using unconventional means to reach the culprit
in Border, it is about a ghost-seeing-detective .
while in Tell me what you saw is about a detective with a photographic memory

both use supernatural means to solve a case
in Voice they can hear inaudible noises
in Who are you through see the dead

both are detective shows about the supernatural with ghosts involved. any more differentiating could be spoiler
but if you liked one you'd like to give the other a try.

both start with the initial same genre, mob BL drama/movie
but then they take two different routes :

you want short the feel good, get off your screen happy and optimistic for the world then pick exhibit A. Long Time no See

If on the other hand you aren't afraid if investing more time and emotions and diving a little deeper into the pessimistic world, on the risk of heartache, Yet! still has an eventual satisfying ending , exhibit B. Moon Child ( Warning : Hyde and Gackt are your leads in this one)

Both with an amazingly high rewatchablity - I know I've been rewatching Moon Child sense I discovred it circa 10 years ago, and I still revisit it once a year
I may have just stumbled upon Long time no see, but it's an easy rewatch as well, if just to see those two look in each other's eyes and hold hands so cutely!! .. maybe I should save a gif of that as a phone background ;?