Knitting is a technique for making fabric by creating loops in a single continuous yarn or thread.
Weaving is the interlacing of two sets of yarn or thread at right angles to form a fabric.
Because of its structure, knitted fabric is more elastic and pliant that woven fabric (compare a knitted T-shirt with a woven pair of jeans).
Other differences…
… Weaving has a set base structure – the width of the fabric in the machine is always 170 cm.
… Knitting does not have a set base structure – you can knit straight lengths, but you can also knit loose panels; the shape is variable.