What’s the Difference Between “Too” and “Also”?

Gaby Beitler writes:

I am confused when to use the word too and when to use also. For example, “he likes ice cream too” and “he also likes ice cream” mean the same thing.

In conversation both words, too and also, are used interchangeably with the sense of “in addition”:
Our friends went too.
Our friends went also.
In such a sentence the too at the end is felt to be more natural than the also. The word also is more likely to go before the verb:
Our friends also went.
The use of too in the sense of “in addition” is not confined to the end of a sentence:
I, too, believe that children are more intelligent than they are given credit for.
They, too, wanted to see the movie.

The word too can be used to modify adjectives:
This coffee is too hot to drink. Here the sense of too is “to a higher degree than is desirable.”
The word also can have the meaning “in the same manner as something else.”
Few young people read Scott anymore. George Eliot is also neglected in today’s school curriculum.

In conversation it doesn’t matter whether you use too or also, or where either falls in the sentence.
In writing it’s a good idea to give some thought to how the words are being used, and to how often you use them.
Here, from my trusty Oxford American Writer’s Thesaurus, are some alternatives for too and also used with the meaning “in addition”:

• as well
• besides
• in addition
• additionally
• furthermore,
• further
• moreover
• into the bargain
• on top of that
• what’s more
• to boot
• equally