1.   But the only difference between these two sentences lies in the choice of the lexical item as object.

2.   The only difference between us is that you have a wife and three kids.

3.   The only difference is a difference of degree.

4.   The only difference is that the work simply does not get published.

5.   The only difference is that they are called taxis.

6.   The only difference now is that he wears a headband, perhaps to keep all of his deep thoughts from falling out.

7.   The only difference now is that people are not surprised and perhaps, therefore, better prepared for the shock.

8.   The only difference was that the Guides could look forward to returning to comfortable homes.

9.   The only difference between us is the colour of our skins.