In general, the low frequency transformer refers to the "power frequency transformer", which works under (50Hz) and is used to change the voltage. The iron core used by the low frequency transformer is generally silicon steel sheet with high permeability
High frequency transformer refers to the transformer that works in high frequency and plays the role of energy conversion. Because of the frequency of magnetic field is very high, the silicon steel sheet will produce eddy current (the conversion speed of the small magnet in the silicon steel sheet cannot keep up), so the high frequency transformer generally USES "high frequency ferrite" as the magnetic core.
The difference between high frequency transformer and low frequency transformer lies in the difference in frequency, the difference in operating frequency leads to the difference in selection. Their working principles are same. They both transmit energy through electromagnetic induction regardless of the high or low working frequency.