Mary was reassured but Zachariah was punished

Why is it that Mary and Zachariah were treated differently by the angel Gabriel in the gospel of Luke?

Why is it that Mary was reassured after her question but Zachariah is punished after asking a similar question?

Lk 1:34-37 But Mary said to the angel, "How can this be, since I have no relations with a man?" And the angel said to her in reply, "The holy Spirit will come upon you, and the power of the Most High will overshadow you. Therefore the child to be born will be called holy, the Son of God. And behold, Elizabeth, your relative, has also conceived a son in her old age, and this is the sixth month for her who was called barren; for nothing will be impossible for God."

Lk 1:18-20 Then Zechariah said to the angel, "How shall I know this? For I am an old man, and my wife is advanced in years." And the angel said to him in reply, "I am Gabriel, who stand before God. I was sent to speak to you and to announce to you this good news. But now you will be speechless and unable to talk until the day these things take place, because you did not believe my words, which will be fulfilled at their proper time."

Mary who is “Full of Grace” (Lk 1:28) and is blessed (Lk 1:48) is reassured and Zachariah, an elderly priest who is worthy of double honor (1 Tim 5:17) is punished.