We use as well and in addition when we are adding information. As well is more informal than in addition.

Notice the position of these expressions. Usually, as well comes at the end of a sentence. And in addition comes at the beginning of the sentence.

As well:

• We look forward to seeing you and meeting your brother as well.
• The house is very spacious, and it’s very close to my parents as well.
• She likes to paint butterflies and gardens as well.

In addition:

• The flat is beautifully furnished. In addition, it is in a good location.
• Part-time English classes are offered. In addition, students can take classes in other languages.
• In addition to her apartment in Chennai, she has a villa in Mumbai.