英文文法--abjective phrase & modifier 既分別??

片語: Adjective phrase

He reached the castle on the mountain

on the mountain---> is adjective phrase

修飾語 (Modifier)

A big tree stands on the top of the hill

on the top of the hill-----> is modifier

我弄不清abjective phrase & modifier 既分別, help me pls !!!!~~~ Thanks