In an ectopic pregnancy, the fertilised egg implants outside the womb (usually in the fallopian tube) and continues to grow and enlarge. The fallopian tube is not designed to support a pregnancy and so as the pregnancy grows, the tube is stretched and eventually will rupture.
A hydatidiform mole, or molar pregnancy, is a medical term which means fluid filled mass of cells. The cells that normally become the placenta grow too quickly and fill the womb where the embryo would normally develop. This means a normal pregnancy cannot develop.