I had the same problem, and decided that the simplest solution was to purchase a 3rd party tool. I bought SQLBalance. It was really buggy, my questions went unanswered, and in the end, I forked out yet more money for Sync Database. It was much more expensive, but at least it worked

So why spend money? Well, I couldn't find any OS solutions, and I needed something at short notice. Generally you can compare the db definitions and generate delta SQL yourself, but there's also possibilities that there may be bugs in your code, and I needed something quick - and which worked. I lucked out with SQLBalance, but at least I discovered the problems in my test run. Sync Database has worked for me, but I personally I think that it's way overpriced.