What a shame to confuse the two. Men with gynecomastia will often wear several shirts. In fact, when patients come into my office, they are often wearing a tight, Under Armor type of a shirt under their regular shirt in an effort to reduce the appearance of their gynecomastia.
While this makes them look somewhat better, there is only one thing that fixes gynecomastia, and that is surgical removal.
Here are examples of what the results can look like: http://www.drteitelbaum.com/body-men/male-breast-reduction-surgery