Expansion of Supply refers to an increase in the quantity supplied due to a fall in price, along a fixed supply curve. It happens when price decreases and producers offer more goods.
Increase in Supply refers to a shift in the supply curve itself, resulting from factors like technology improvement or lower production costs, which increase the supply at all price levels.
Final Answer:
\[
\boxed{Expansion \; of \; Supply \; is \; a \; movement \; along \; the \; curve, \; while \; Increase \; in \; Supply \; is \; a \; shift \; of \; the \; curve.}
\]