A frequency range test presents 25 tones, and asks whether you can hear them. From this, it tells you your highest and lowest audible frequencies, your "hearing age", and a fun animal that represents your hearing abilities.
A frequency differentiation test presents 25 tone pairs, and asks if you can hear a difference. The results tell you what frequencies you can differentiate over the hearing spectrum and suggests an instrument based on your answers.
Please take care with this application by reading instructions as they are presented. When the test is done, read about the results, and try each ear individually!