Osmocote plus includes Macroelements (Nitrogen, Phosphorous, and Potassium) and Microelements (Magnesium, Copper, Boron, Iron, and others). Regular Osmocote only contains the macroelements.
What type of lighting do you have on your tank, and what type of plants do you have? If you don't have a ton of lighting, and your plants aren't very needy, I could see you getting away with using regular Osmocote. In a high-light setting with needier plants, you would probably want to find a way to incorporate some micros into the tabs.