Well... not much difference haha. Their definitions are completely the same, but you mainly have to watch where you place them in sentences the phrase "as well" fits this meaning, as well.. :P fits this meaning too fits this meaning also "Too" is not as common, while "also" is far more common. "I can also go with them" sounds completely natural, but you cant use "too" or "as well" in the same place. "Too" and "as well" you will usually find at the end of a sentence, and never at the beginning, but "also" can be placed in many places in a sentence "Also, I can go with them" "I also can go with them" "I can also go with them" or "I can go with them also" But with "too" you can only say "I too, can go with them" or "I can go with them too" The only way to use "as well" here would be "I can go with them as well" Hope this helps :)