What's the difference between 'addictive' and 'addicting'?

Solution 1:

Addictive is an adjective meaning something is addictive.

Addicting is a verb — meaning to do something to become addicted. "I am addicting myself to caffeine by drinking so many espressos".

Solution 2:

The meanings reported by the NOAD for addictive are:

• (of a substance, thing, or activity) causing or likely to cause someone to become addicted to it
• of, relating to, or susceptible to being or becoming addicted to something

Addicting is, as the dictionary reports, the informal equivalent of addictive.
Both addictive and addicting are correct; only the context where the word is used changes.

Addict is a noun that means "a person who is addicted to a particular substance, typically an illegal drug." Its etymology is early 20th century, from the obsolete verb addict, which was a back-formation from addicted.

Solution 3:

'Addicting' has only started to become noticeable in recent years, and I only ever see it in relation to games. Usage as a verb is apparently valid although it does look and sound very wrong!

Solution 4:

As it is associated with gaming I suggest that the use of addicting is incorrect, probably introduced by children who haven't learnt enough yet, because they spend too much time playing video games and not enough time learning to speak.

The suffix determines the meaning of the word and in this case Martin Becket is without a shadow of a doubt correct.