Yes, different pastes will have different flavors. Further, one brand in one area can taste different than the same brand in another area. Fun, huh.
Your best bet is to go to your local food coop /WHole Foods/Central Markup and buy a good quality organic paste. It will cost a little more, but it will have a really good flavor. Try altering the herbs you use in your mix as well. I simmer my sauce for a full day.
Their are several reasons for the varying flavors
1- Quality of tomatoes used... Along with variety, ripeness, etc.
2- Herbs and other flavorings used in the cooking process
3- Canning process can alter the flavor, along with prolonged exposure to oxygen...
I hope this helps.