In Compression Zones like columns and walls, where max loads are in the direction of gravity.
Rebar transfer the load from 1 bar to other lapped bar.
Wheras in slabs and beams, i.e. - tension rebar has to take all tensions in mber and transfer some stress to concrete .
Work of rebar is more in tension than compression.
In Compression almost 25% bond stresses get reduced.
For this we have lesser ld in compression compare to tension.