From Wiki
Align clip defines how the object is aligning to the terrain when dropped or move on the ground.
| Attribute |
Description |
Setting |
| AlignSnap |
When an object is dropped onto the ground, AlignSnap aligns X, Y, Z (translation) to the terrain.E.g. horse and human which keeps vertical to the sea level
 |
Data Type:BOOL |
| AlignFollow |
When an object is dropped onto the ground, not only the Move X, Y, Z of the object adjust automatically, but the rotation of the X, Y, Z also adjust to match the angle (normal) of the terrain.E.g. cars, tanks, lizard and ants.
 |
Data Type:BOOL |
Reference Tutorial:
Grab and Drop