Hepatitis A is the most common type of infective hepatitis. It is not a sexually transmitted infection, and is usually spread through contaminated food or water. It is not very common in the UK and most people who contract the infection recover fully after several weeks.
Hepatitis C is a common cause of chronic liver disease. It is usually asymptomatic and is generally accepted to be the most serious hepatitis infection. The virus is spread through blood contact, or contact with other bodily fluids, though this is far less common. There is a slight risk of spreading the infection through unprotected sexual contact, but this is very rare and hepatitis C is not considered to be a sexually transmitted disease.