En el invierno, nieva.
En el invierno, nieva. & Nieva en el invierno.
Similarly,
En la primavera, llueve. & Llueve en la primavera.
Both seem to make sense, but the videos say the first is correct. I know with many aspects of Spanish, you order things differently than you do in English.
2 Answers
For me both are corrects. I can't see any difference.
Both are correct as far as i know, but the stress differs. In the first sentence "En el invierno nieva"you are just saying "It snows in the winter, as a general observation".In the second sentence "Nieva en el invierno", you are stressing that it snows in the winter (as opposed to other seasons). I think that using "Nieva" first conveys a sense of emotion, or a stylistic effect.