Both dramas have the same silly, sweet and funny feel with a charming female lead.
Also, Kim Hyun Joong (Yoon Ji Hoo in Boys Over Flowers) is the male lead in Playful Kiss. His character (Baek Seung Jo) is different yet somehow still similar to Yoon Ji Hoo. So, if you liked him in Boys Over Flowers, you'll probably like him in Playful Kiss as well!
Also, Kim Hyun Joong (Yoon Ji Hoo in Boys Over Flowers) is the male lead in Playful Kiss. His character (Baek Seung Jo) is different yet somehow still similar to Yoon Ji Hoo. So, if you liked him in Boys Over Flowers, you'll probably like him in Playful Kiss as well!