There is a difference.
There's a question on the Massachusetts ballot this November which would decriminalize marijuana use...it would replace the criminal penalties for possession of up to one ounce of pot to a civil penalty of forfeiture of the marijuana and a fine of $100.
A recent poll conducted shows that 72% of the respondents agree and will vote yes. In fact, I was going to ask why you were even posting this since polls have shown the majority of Democrats support decriminalization but then I remembered...you're not a Democrat.
http://www.suffolk.edu/30284.html