Is there a difference between the pain caused by tooth decay, sensitive teeth and sinus pain?

A bit tricky: These 3 causes of pain can be a bit tricky to sort out sometimes. If tapping on the suspected tooth increases pain, then it is probably the tooth. Sometimes a troubled tooth causes sinus problems. Sometimes the maxillary sinus (one under your cheek bone) problem causes enough pain to feel like it's in the upper teeth. So, it is best to see your doctor and/or dentist to help sort it out.

See A Dentist: See a dentist, as there are some evaluation methods that can be used by the dentist to determine what is causing your pain.

Yes: Sensitive teeth are usually caused by exposed dentin and can happen in any tooth. Not that intense and goes away as soon as the offending source (like a cold drink) is removed. Tooth decay when it gets close to the nerve will cause more intense pain and will come and go on its own in addition to reacting to stimuli. Sinus pain often feels like a toothache - only on upper teeth usually molars.