Smooth muscles are present throughout in your body. It is mostly found in your stomach and intestines as it helps in digestion and nutrient absorption. Also, it can be found in your unrinary system, it contributes in electrolyte balance and removing of body toxins.

Both smooth muscles and cardiac muscles are involuntary unlike skeletal muscles. Cardiac muscles are found in your heart. It helps in causing your heart to pump blood throughout the rest of the body. It is again an involuntary movement required to sustain life.

Again, skeletal muscles are different. It is voluntary movement, which means you will be the one to control your own body or your muscles on how and when you decide to. The nerves in your somatic nervous system are sending signals to make them function. For example, walking.

Sources: https://www.ncbi.nlm.nih.gov/books/NBK526125/ https://www.sciencedirect.com/topics/medicine-and-dentistry/cardiac-muscle https://my.clevelandclinic.org/health/body/21787-skeletal-muscle