I would definitely go with AdeptSQL if you're using MSSQL. It's the least good looking but the most talented db compare tool amongst the ones I've tried. It can compare both the structure and the data. It tells you which tables exist on one db but does not exist on the other, compares the structure and data of the common ones and it can produce the script to synchronize the two. It's not free but has a 30 day trial (as far as I can remember)