The Lost Tomb is the first in the series as well as the place where Wu Xie, Zhang Qiling and Pangzi meets (aka, the Iron triangle). It gives a plot start to this whole adventure.

Both has similar settings as my youth is mostly set in school whereas Youth Unprescribed is more university. Both dramas has a light hearted and fluffy feeling thus if you want to watch something make you feel happy , then give these a go.