* 200 cm: There are 100 centimeters (cm) in 1 meter (m). So 200 cm is greater than 1 meter.

* 20 mm: There are 10 millimeters (mm) in 1 centimeter (cm), and 100 centimeters in 1 meter. Therefore, 20 mm is less than 1 meter.

* 2 dm: There are 10 decimeters (dm) in 1 meter. So 2 dm is less than 1 meter.

* 2 km: There are 1000 meters (m) in 1 kilometer (km). So 2 km is greater than 1 meter.

In summary:

* Greater than 1 meter: 200 cm, 2 km

* Less than 1 meter: 20 mm, 2 dm