Yes that is true... Also, too and as well CAN mean that - it's an agreement. For example, "You think that English is a difficult language to learn. I do too" "You think that English is a difficult language to learn. I also find it difficult" "You think that English is a difficult language to learn. I do, as well" It is agreement. Too can also be used as a size dimension - "it is too big, it is too difficult..." If your TV is too big - it means that maybe you cannot use it - it cannot fit onto your TV stand! On the other hand, we also use "also" and "as well" to start a new discussion on a topic. This is expecially important when writing essays as it shows that you can structure a coherent piece that is held together with all of the sentences linking. For example, "As well as the TV being too big, the picture was all fuzzy and I could not watch it. I also have a radio that does not work". Too cannot be used in this way. "Either" can be used in the same way (as Jared said) in negative statements...but AS WELL (!) as this it can be used where there is a choice to be made. For example, "Either you fix my TV and my radio, or I want my money back!" "The TV is either too big or too small, it cannot be both"

Also, too, and as well all mean the same thing. Generally, "also" is used before the sentence, or after the subject ("I also eat. Also, I eat"). "Too" is used after the sentence usually ("I eat, too"). "As well" is commonly used at the end of the sentence ("I eat, as well"). "Either" is basically the same thing as "also," "too," and "as well," but it is used in negative statements ("I don't eat, either").