Why Is Alphabet Worth More Than Apple?

For all intents and purpose, Apple and Alphabet are tied in the superficial race to see who has the largest market cap. Alphabet surged to take the token title of "world's most valuable public company" earlier this week in the wake of a strong fourth-quarter earnings release, only to give it back to the Mac maker just a couple of days later.

Let's just call it even. But as both tech giants boast similar market caps, their valuations are still drastically different. Why is that?