Many consonant sounds come in pairs. For example, P and B are produced in the same place in the mouth with the tongue in the same position.
The only difference is that P is an unvoiced sound (no vibration of the vocal cords) while B is a voiced sound (vocal cords vibrate). Put your hand on your throat as you say the pairs below to feel the difference.
Note that the first pair of consonants in the table (p, b) is produced at the front of the mouth. Each pair shifts further back with the last pair (k, g) being produced in the throat.