Hello Fabrizio. Thank you for your question.
Both anyhow and anyways are adverbs and they have much in common. Anyhow can be replaced with anyway but not with anyways.
Anyways is an informal version of anyway. Some grammarians are of the view that anyways should not be used else you will be considered as illiterate. Anyways is just a modern version of anyway.
To make it easier for you, you should use anyways if you are trying to say something informal. use anyway if you are saying something formal. Both of these, anyhow and anyways are adverbs and can be used interchangeably when used as conjunctive adverbs.
I hope this helps.