Difference between: Also, too and as well [duplicate]

I understand that the correct usage of also is with a verb:

She was smart, she also studied so much.

However, my trouble is with too and as well, I have been reading and I just found that as well is not common in American English, and regarding with the examples that I have found, those adverbs have the same meaning and you can use them in the same way and always at the end of the statement.

She was smart, she studied so much as well.
She was smart, she studied so much too.

How much of that information is true?

The adverbs also, as well and too have similar meanings, but they do not go in the same position in sentences. Also is usually used with the verb. Too and as well usually go at the end of a sentence or clause. Note that ‘as well’ is not very common in American English.

He not only plays; he also works.
He was fat, and he was also short.
He not only plays; he works as well.
He was fat, he was short as well.
He not only plays; he works too.
He was fat, he was short too.

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