What is the difference between ‘toBe’ and ‘toEqual’ in Jest?

It fails cause x and y are different instances and not equal as in (x === y) === false. You can use toBe for primitives like strings, numbers or booleans for everything else use toEqual. For example

x = 4 
y = 4
x === y // true

x = 'someString'
y = 'someString'
x === y // true

Even empty objects are not equal

x = {}
y = {}
x === y //false