The directional particle へ could be said to be a more literary version of the target particle に when the particle is used to denote a direction of movement. It is rarely ever used in conversation, but will be seen in the JLPT examinations from N5 onwards.
学校に 行きます。
I will go to school.
学校へ 行きます。
I will go to school.
友達に 手紙を 送ります。
I will send a letter to my friend.
友達へ 手紙を 送ります。
I will send a letter to my friend.
Nor does the direction of movement need to be physical.
【A】から 【B】に 変ります。
To change from A to B.
【A】から 【B】へ 変ります。
To change from A to B.
The へ particle cannot, however, be used to mark an objective, as a location marker, or as a time marker.