Hard Fork

Well at first it sounded like an aroused utensil, however it wasn't that arousing for the Bitcoin community.
A hard fork is technically a change in the protocol where their is a possibility of a network split ( community split ), this happens when a big portion of the community don't agree with the update.
This lead to two different currencies like Bitcoin and Bitcoin Cash, hard forking is not backward compatible so not all nodes can communicate together unless they are in the same updated network, the history of the blockchain is shared till the fork.
Hard forking is important when the community wants to change the block structure.

Something significant to keep in mind is the fact that hard forking is prone to splitting the community by having two coins and two networks, this makes you vulnerable to replay attacks.

What do i mean by replay attacks?
Lets just say Monk had 1 BTC before the hardfork,
after the hardfork Monk still has his 1 BTC but also has 1 BCH,
this happens because you will get an equal amount by default of what you had previously when the fork happened.
Now if Monk send 0.5 BCH to Trump and Trump is a malicious fraudulent person, he could replay that transaction to himself through the BTC network. So instead of Monk sending 0.5 BCH he theoretically sends 0.5 BCH and 0.5 BTC to Trump.

If you are still bewildered by the term replay attack watch this video.

Soft Fork

Not much to say about this flaccid utensil...only a change in the protocol, however it is still backward compatible, making all nodes still able to communicate together. Soft forks do not require old nodes to upgrade and maintain consensus, because all blocks on the softforked blockchain follow the old set of consensus rules as well as their new ones.