How to work with Distribute in object menu
To work with Distribute in object menu
a) Distributing Objects Horizontally
When you distribute vector objects horizontally, the objects closest to the left and right boundaries of the group become the two target objects. The distance between these target objects determines the distribution, or spacing, of the objects in between them.
There are three types of horizontal distribution:

Left distribution, where objects are evenly spaced between the left edges of the left and right targets.

Center distribution, where objects are evenly spaced between the centers of the left and right targets.

Right distribution, where objects are evenly spaced between the right edges of the left and right targets.
b) Distributing Objects Vertically
When you distribute vector objects vertically, the objects closest to the top and bottom of the group boundaries become the target objects. The distance between the two target objects determines the distribution of the objects in between.
When you distribute objects vertically, the distance between the object closest to the top and to the bottom edges of the group determines distribution.
There are three types of vertical distribution:

Top distribution, where objects are evenly spaced between the top edges of the top and bottom targets.

Center distribution, where objects are evenly spaced between the centers of the top and bottom targets.

Bottom distribution, where objects are evenly spaced between the bottom edges of the top and bottom targets.