I've read recently somewhere that most "soaps" are actually detergents and the real soap would not be a good idea in everyday applications like washing hands, shower gels and shampoos, and dish washing liquids. But I couldn't find a sufficiently detailed explanation about the differences of the two, just that the detergents are often marketed as soap.
Are they really different? What negative effects does soap have that detergent doesn't? Is there something soap does that detergent doesn't do?