[dan1123]

Here’s a double pun with a grammar lesson:

What’s the difference between a cougar and a comma?

One has claws at the end of its paws, and the other’s a pause at the end of a clause!

[Petronski]

From the late great Red Foxx:

What's the difference between a pickpocket and a peeping tom?

The pickpocket snatches watches.