What is the difference between these two tires?

I was looking through tires on a website and found two that looked to be the same with the exception of a single letter. They are both Continental Contiprocontact.

P 235/45 R18 94H SL BSW GM

235/45 R18 94H SL BSW VM

The stats all look the same except the 2nd one has a higher max pressure, 51 psi vs 44 psi. The VM is also $8 more expensive.

It seems odd that Continental would sell 2 tires with the same brand name and same size. I've seen General do something similar but in the General tire case, one tire was V rated and the other was H rated so I could tell what the difference was.