What is the difference between 50 Hz and 60 hz and which is better?

Well, this is not question of better or worse. These are standarts of alternating current (AC electricity). It means that charge changes its direction (or) times per sec. Hz andV is standart for USA.Hz andV is standart for some European countries. But nowdays all the charging adapters support dual standarts.

The frequency affect the inductive loads ( particularly AC motors) directly as the speed of motor is directly proportional to Frequency and inversely proportional to number of poles.

The fifty HZ motors will run twenty percent faster than Sixty hertz motor when connected with sixty hz supply source. It may give undesirable result as the motor is not designed for over speed running continuously and process connected to motor will have adverse effect. the process speed can be controlled by introducing control gear in between motor and process.

The sixty hertz motor can be run on fifty hz supply by reducing the voltage fifty HZ/sixty Hz x hundred percent. .i.e. eighty percent of sixty hz motor voltage mentioned on name plate will give same speed as of fifty hz.

Fifty Hz or sixty Hz depends on power generation equipments.

Well, nowadays motors, chargers and other electrical equipments are available with both frequencies, if you see the smart phone charger, then you will see compatibility of to Hz, similarly if you see some motors, whether they are or, they will perform same in and hz, this is because the variation between these two hz is common, and it is difficult to say which one is best, because I think most of the people only see two things, one is voltage and other is wattage, buyer will see only these two things, they will not see whether it ishz orhz compatible. I think I have answered it according to question asked.