What is the difference between a disc plough and a disc harrow?

Disk Plow

It is a primary tillage implement with an individual disk of size 60cm or 90cm connected to stub axis. The disk angle and tilt angle are subjected to change in disk plow. The field after plowing with disk plow result in large soil clods and uneven topography.

Disk harrow

It is a Secondary tillage implement with a group(gang) disk of size 40cm or 60cm used after primary or disk plow. Similar to disc plow but discs are uniformly spaced along a common axle or gang bolt and clamped together through spacer spools so the entire gang rotates as a unit. So naturally, no disk angle and tilt angle but ‘gang angle’. The field after plowing with disk harrow result in tilled soil without any large clods and even topography.