What is the difference between vector and carrier  ? 

 a disease vector itself is a carrier. you must want to know the difference between a disease vector and a disease reservoir.

a vector is a carrier (mosquito, tick) that takes the disease from an infected individual to an uninfected individual. They do not have the disease themselves, they carry the infected agent such as blood. A reservoir is any thing (person, animal, arthropod, plant, soil or substance) in which a disease lives and can multiply. The disease NEEDS the reservoir in order to survive. A vector must be living but a reservoir can be a non living thing such as soil or water. Neither actually HAVE the disease but are simply transmitters.