Bite is different. With a dislocated jaw, the teeth will not meet properly (the way they met before the dislocation). It is best to have the problem diagnosed quicly before permanent damage to the joint occurs. Go see a dentist quickly.
Opening limited pain. A normal jaw should be able to open around 48mm or the height of 3 fingers and this movement should be painless and noiseless. If you cannot open this wide and hear noise or pain your jaw is probably affected and may be dislocated. Conservative measures like a splint and/or physical therapy are good help to find a better place for the joint to function. Check with your dentist or get a referral.