I assume when referring to difference you mean differences other than weight? Obviously the 150's are lighter than the 180's. To do this bullets of equal diameter (.308 for 30-06) are made longer to get the extra weight. If both bullets are of equal construction the heavier bullet will usually penetrate further than a lighter bullet. There are alot of other things such as sectional density and ballistic coeffient that can factor penetration, trajectory and accuracy. I am taking a guess here and trying to figure why you are asking. Are you trying to pick the correct bullet for your gun? Take into concideration the animal you are shooting, the range you are shooting, and what performs well in your gun. If you give us some more details we can help out a little more.