Kellog's 1Y program is a perfect fit for those who wish to accelerate their career with a shorter program. 1Y program is different from 2Y program in many ways. 1) smaller size. 2010 1Y has a class size of 86, while 2011 2Y program has a class size of almost 460(including MMM and JDMBA) 2) 1Y program require students to have a strong background in the business arena, so the student is able to waive most of core classes such as Finance 1, statistics, accounting, etc. So that 1Y students will be able to take full advantage of the 1Y program to take elective classes. 2Y program allows students to have time to take core classes + some elective classes in the first year. 3) starting time is different. 1Y students start their program from June, while 2Y students start their program in late August. 4) cost is different, 1Y program is about $65,000 for tuition while 2Y program is about $48,000/year for tuition.
hope that answers your question. by the way, the two programs give out the same MBA degree.