Have you tried looking at photos, or just using your eyes in general?
You could also do a simple Google search.
But don't worry, I'm here to spoon feed you like a baby, pic related.>>3878641
You're just making yourself look more stupid.>>3878642>It is the focal length
No, it's the subject to camera distance. If I take a photo of someone's face from 10m away with a 12mm rectilinear lens and a 200mm lens, they will look identical.
If I use a 35mm lens to take a photo of someone from 10m away, it will have a very different look to the facial structure than if they were half a metre away.
Effective focal length also changes with sensor size, but perspective distortion does not, because perspective distortion is due to the subject to camera distance only.
Don't worry, if you samefag some more, then I'll keep calling you out as a moron in every post. Even if you learn to capitalise the first letter of your sentences, I'll still know which ones are yours petal.