A resemblance is a similarity in appearance. Children usually have a strong resemblance to their biological parents.
When you talk about resemblances, you're talking about people or things that look alike in some way. Relatives often have resemblances because they share the same genes. Perhaps you have a resemblance to a famous person. Many people think there's a resemblance between dogs and their owners. If someone draws a picture of you, but it has no resemblance to what you really look like, they did a bad job.