As mentioned above, the "Junior Cassettes" tend to have a larger first sprocket.

But, that is all relative with respect to your chainring.

So, say you have a 52/14 high gear, you would have almost the same gearing by going with 41/11.

However, if you have, say a 11/25 and a 14/28 cassette, the 11/25 actually has a slightly wider gear range, despite having a smaller low gear.