Drawback: London is an amazing country to visit, however, the only drawback is the weather.
Drawback is defined as a disadvantage or the negative part of a situation.
Counterpart: He gathered with his counterpart in order to discuss about a serious issue.
Counterpart is a person or thing that has the same purpose as another one in a different place or organization.
Another option could be to use both words in a sentence such as: The only drawback of meeting her counterpart is that he may manipulate her to lead the situation.
The salutation is to greet the person you are addressing, it goes before the introduction. The introduction is a brief summary of the letter itself and the body is the letter itself.
