Hard rock is typically louder and more aggressive sounding than rock. Rock music often features slightly distorted guitars that are still played relatively cleanly, while hard rock typically uses very thick-toned, heavily distorted guitars to give it its signature sound. As well, rock drummers might play fairly clean and straightforward beats, while a hard rock drummer will typically play busier, messier beats, such as pounding a crash cymbal or loose hi-hat to give power. While hard rock might focus more on power and intensity, rock music tends to gravitate more to melody and catchiness.
While each genre certainly has a variety of lyrical subjects, hard rock often has darker lyrics than rock music. This can include lyrics about depression, anger, religious incredulity and more. Rock music often aims for catchier, more fun lyrics, as opposed to hard rock and its typically bleak words. As well, hard rock often uses more vulgarities in lyrics, so it's not uncommon to find stickers warning about lyrical content on hard rock releases.
Persona is important to any genre of music, and those who play rock and hard rock don't forget it. Similar to the more aggressive music and lyrics, hard rock often has a mean or tough attitude that bands portray to the public and their fans. This attempts to add legitimacy and credibility to the music they make that often carries these similar themes. At the same time, rock musicians often adapt a tough attitude, but in a friendlier sort of way. They try to have an edge, without potentially offending other people.
Each genre has its notable bands. Many of these bands have existed in the last few decades, and some still exist today. As well, new ones pop up in either genre all the time. Some famous rock bands include The Black Crowes, Faces and The Beatles. Some famous hard rock bands include Black Sabbath, Stone Temple Pilots and Guns n' Roses.