Computing power is more used as a general processing power (outside of bitcoin), and isn't really important for bitcoin network. More important for how fast you can open video on your computer or run video games, or make some complex calculations, etc. (to put it simply). So 'computing' uses operations per second, and hashing uses a number of 'hashes per second'. Early on, it turned out that some computers could be much weaker in computing power, but could run hash function much faster, and vice versa. So all mining computers were designed to do just 1 function - hashing. Computing power became kinda useless as efficiency measurement, so hash power became standard measurement unit.
Computing power is more used as a general processing power (outside of bitcoin), and isn't really important for bitcoin network. More important for how fast you can open video on your computer or run video games, or make some complex calculations, etc. (to put it simply). So 'computing' uses operations per second, and hashing uses a number of 'hashes per second'. Early on, it turned out that some computers could be much weaker in computing power, but could run hash function much faster, and vice versa. So all mining computers were designed to do just 1 function - hashing. Computing power became kinda useless as efficiency measurement, so hash power became standard measurement unit.