There are basically two kinds of lapels available for men’s suits – peak and notch. The peaked lapel is usually associated with double-breasted suits and dinner jackets.
The peak has a distinctive point, and makes for a formal and potentially powerful look that can seize the attention. The statement is “I’m in charge,” and you should avoid peak lapels when a more discreet or less aggressive feel would be appropriate – in job interviews, for instance, or for everyday office wear.