What's the difference between Acne and Impetigo?

I was in 8th grade at the time, When I'm really bored, I always pop my pimples, hoping that the white stuff comes out, and I sorta enjoyed doing that. But my teacher saw me and said that this "acne" is actually impetigo. But it's just a pimple. what's the big deal! My mom and I went to a doctor, she said the same thing! It's just a pimple, why do I have a feeling i'm being misdiagnosed.

What's the difference between Acne and Impetigo, what causes impetigo?

If possible show some pictures.

Your teacher is ignorant (that means ill-informed). Impetigo is a skin infection caused by bacteria. Usually the cause is staphylococcal (staph) but sometimes streptococcus (strep) can cause it, too. It is most common in children between the ages of two and six. It usually starts when bacteria get into a break in the skin, such as a cut, scratch or insect bite.

Symptoms start with red or pimple-like sores surrounded by red skin. These sores can be anywhere, but usually they occur on your face, arms and legs. The sores fill with pus, then break open after a few days and form a thick crust. They are often itchy, but scratching them can spread the sores. Impetigo can spread by contact with sores or nasal discharge from an infected person. You can treat impetigo with antibiotics.

Impetigo is highly contagious-do not touch your face and touch anyone else! it can be spead easily!!

Your lesions (open sores of any kind) can lead to Impetigo
which is a contagious skin rash. It oozes but if you had a pimple it's simply that.. although the lesion left could lead to impetigo!