If you think of a blockchain as a path, a hard fork would be a fork in the path. If the miners agree on the further path of the currency, a direction is decided together and this path is then taken.
Now it can happen that the miners disagree on which way to go. If this happens and there are two strong groups (factions) with different ideas, the existing block chain is divided. Up to the point of the hard fork the block chain is identical, after that the ways separate.
Then it can also happen that 2 different crypto currencies are formed from it, as happened with Bitcoin Core and Bitcoin Cash.
This is quite connected with risks, because if the users of the currency do not find a way well and ignore the currency, it loses its value fast. Therefore, the miners naturally try to find a solution that the community is satisfied with. The miners can determine the further path of the currency, but the currency loses its value without users. Therefore, it is important that all participants work together to avoid hard forks that split the community.
