Need a simple explaination for this. what is a cross bite and over bite?

Simple, I hope: In an ideal bite the upper teeth are slightly wider than the lower teeth and the lower teeth slip to the inside. When this is reversed you have a cross bite. Overbite is often miss used. The lower front teeth should slip behind the upper front teeth for a short distance, like two millimeters. Many people function just fine with these conditions, for others it's traumatic and shortens life of tooth.

Wrong Jaw Position: Over bite - when the lower front teeth are retruded back so they are not touching the upper front teeth. Cross bite - when the upper back teeth are not closer to the cheek than the lower back teeth - need to check both the left and right sides as they can show this problem differently.

Cross\Over Bite: In simple terms- overbite: the degree that the upper teeth cover the lower teeth. Crossbite: when the upper teeth are positioned on the inside instead of the outside of the lower teeth. See: http://www.Webmd.Com/oral-health/tc/types-of-malocclusion-topic-overview.

Malocclusion: Crossbite: top teeth inside bottom teeth. Horizontal overbite (overjet): top front teeth more than 2mm in front of bottom front teeth (buck teeth). Vertical overbite: top front teeth overlap bottom front teeth by more than 2mm (deep bite). Causes may be dental, skeletal,or both. As no 2 malocclusions (bad bite) are alike, see a qualified Orthodontic Specialist for evaluation and treatment.