In certain usages they can mean the same thing. For example, "I am hungry too." or "I am hungry also". However, if you reverse some of the words then the meaning changes. For example "I am too hungry" means something similar to "I am very hungry", however "I am also hungry" means the same as "I am hungry also". So "too" can mean the same thing as "also" or it can mean something similar to "very" or "so". I hope that didn't confuse you.