Hi there! There is not much of a difference between these words as they are synonyms. I hope that this helped. :)

As so often in English, there is more than one word for something. ‘Frequently’ is more formal or official ; ‘often’ is general purpose.

There is no difference really you can use them interchangeably

Frequently and often are essentially the same. Frequently describes a relationship with ongoing action. Often means a lot of times during the defined period.