There are not major differences but some that I will mention. The straw chopper final drive belt and pulleys on the 06 are an upgrade and are better. Cast pulleys, 2-v belt. I have upgraded my 05 to be the same. The Fieldstar system is much nicer better screen, etc. The difference in the engines was not that noticable to us. The 06 might have used a little less fuel. The power seemed very similiar. Other than that I cannot think of many other differences.