Is there much of a difference between Microsoft Excel 2010 and 2013?

There is not much difference. Some older things have been retired, like different chart types, for example cones. The ribbon's look and animations have had small changes. There are some other cosmetic changes you will notice when you use it. They have done things to improve the use of Fill, Charts and Pivot Tables. It is really a case of Office that has been upgraded, so there are only a small amount of changes in any of the individual applications, rather than major changes in each.