The Rashi is the sign in which Moon was placed at your birth time. It's also called the Moonsign. The Moonsign is one of the most important points in Vedic Jyotish. Considerations like the planetary dasha, transits etc. are made in reference to the Rashi.
Ascendent describes your physical personality, appearance and overall health of the person born in that rising sign. Each sign has its own peculiarities and characteristics as per their sign. Read yours