I think there is some difference. The way I learned them, と emphasizes mutuality, while に is more one-sided.
AはBに似ている = "A looks like B"
AはBと似ている = "A looks like B (and B looks like A)"
For example, a situation where と can't be used is when you say "My sister looks like Angelina Jolie." The relationship is not really mutual because you would never say "Angelina Jolie looks like my sister.".