Difference between using `const` and `function` to declare a function

I am relatively new to JavaScript and in my time learning I have noticed that people decalare their functions/components using

const

const

and also

function

function

.

E.g. Using function

function MyComponent(props) {
return <div></div>;
}

function MyComponent(props) {
return <div></div>;
}

And using const:

const MyComponent = (props) => {
return <div></div>;
}

const MyComponent = (props) => {
return <div></div>;
}

What are the differences between the two and why would I use one over the other? Thanks