Which iPhone should I buy and what are the differences?

Probably not a lot except the chip, camera and features they use in different iPhones. The 15 will last a year longer that Apple supports it.

Vevette17 wrote:

Do you recommend buying Apple iPhone 14 or 15? Does anybody find a difference between the two?

You can compare the two models here:

iPhone - Compare Models - Apple

Note that Apple no longer sells the iPhone 14.

You should give some serious thought to the iPhone 16e. It has many of the same features as the 14 but it has a much newer chip, it's lighter, it supports Apple Intelligence if you want that. And you can buy it from Apple.