Have them both in meters.
Use the conversion: 1m/100cm x 600cm/1 = 6m.
So, 600cm = 6m
The 60 meters is already in meters, so it can be kept the same.
Now that they are in the same unit, we can easily compare:
60m > 6m
So, the 6m is shorter and a smaller amount.
Hence, 600cm is smaller.
Hope this helps! :)