Fist: you forget "as well". This has similiar meaning. "Also", "as well", and "too" can change most parts of a sentence with the meaning "in addition". At the beginning of a sentence, "too" is not used. "Also" usually goes next to the verb. At the end of a sentence, "also" is not used. Good examples. My birthday's on Wednesday. Also, my daughter's birthday. As well, my sister's birthday. My grandfather's birthday is also on Wednesday. My uncle's, too. And two of my aunts as well. Bad examples, not used. *Too, my youngest cousin's birthday is on Wednesday.*BAD *Her friend Alice's birthday is on Wednesday also.* BAD "as well as" is a strong way of saying "and". To say "A as well as B" means that A is new information and B is old information. Example. "They speak French in parts of Italy (new information) as well as in France." A and B can be subjects, predicates, or verbs Example (subject) "Alice as well as Paula was shocked by the news." (Short subjects, singular verb.) (subject) "The boring voice as well as the long tedious lesson were a pain." (Long subjects, plural verb) (predicate) "I write poems as well as novels." Note. Here is the literal use of "as well as" meaning "to the same level of goodness as": "I write music as well as I play the piano" - that is, not well at all. (verbs) If the A verb is normal, the B verb is the -ING form. Tobacco is bad for you, as well as making you smell bad. Tobacco makes you smell bad, as well as being bad for you. If the A verb is a base verb with TO, the B verb is the base verb with or without TO I want to explain things clearly, as well as (to) cover the detail. They want me to clean the house as well as look after the children! I hope this is useful.

"too", "also", "as well" are the same. But "too" and "as well" are usually go at the end of a sentence/clause.

There are a few differences but my time right now is limited so I'll only point out one. Typically speaking, "too" is less formal than "also".