toBe(true) vs toBeTruthy() vs toBeTrue()

What is the difference between expect(something).toBe(true), expect(something).toBeTruthy() and expect(something).toBeTrue()?

Note that toBeTrue() is a custom matcher introduced in jasmine-matchers among other useful and handy matchers like toHaveMethod() or toBeArrayOfStrings().

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The question is meant to be generic, but, as a real-world example, I'm testing that an element is displayed in protractor. Which matcher should I use in this case?

expect(elm.isDisplayed()).toBe(true);
expect(elm.isDisplayed()).toBeTruthy();
expect(elm.isDisplayed()).toBeTrue();